What Is Google Maps?

Google Maps is a lot of different things all under one roof. In this chapter, we divide the Google Maps household into three categories: applications, data and algorithms.

As we saw in Chapter 1: Introduction to Google Maps, Google Maps is a lot of different things all under one roof.

In this chapter, we’ll divide the big Google Maps household into three categories:

  • Applications (the products that we engage with as Google Maps users)
  • Data (the information that they present to us)
  • Algorithms (the complex digital machinery that ties the data to the applications– how it all works)

That’s not to say that Google Maps is just an umbrella name for a variety of disparate things. Everything that we’ll talk about in this chapter is related in some way, making up the whole of what Google Maps is.

For example, while features like Street View and Explore are rolled into the main web and mobile apps, we’ll explore them in their own right as distinct applications. This gives us a way to organize the often overlapping and repeating aspects of Google Maps – and helps us understand the full extent of what Google Maps really is.


Applications (or apps) are what we use to interact with Google Maps. They’re the Google Maps product.

Web app

![Google Maps in the Google Chrome browser.](03 Google Maps in the Google Chrome browser.png)

Google Maps in the Google Chrome browser.

First came the web app. This is how you access Google Maps from your desktop or laptop browser. It’s the most popular web mapping service in the world.

Here you can use all of the Google Maps features – Directions, map type and detail layers, Explore and more.

Mobile apps

Google Maps mobile app for Android

Google Maps mobile app for Android

Mobile apps for iOS and Android brought Google Maps into billions of pairs of hands where it was most useful – out and about while driving, using transit, walking, cycling and even flying.

Combined with GPS technology in smartphones, Google Maps and other early mobile mapping services started to revolutionize the way we get around.

These days, you have essentially the same features available on mobile apps as you do with the web app– plus the ability to download maps for use offline (which means you can still navigate with GPS on flight mode – a great way to save your phone’s battery).


Google Maps apps can be tailored to your needs – whether you’re looking at transit routes and stations or trying to find the biggest hill in your city. You can use two types of layers – map details and map types – to display more information, or show you where information is stored.

Map Types: Map, Satellite and Terrain

Respectively, these layers show the map in a standard map display, satellite and airplane imagery, and a map display with hills and gradients visualized with shading.

![Standard Map Type](05 Standard map type.png)

Standard map type

![Satellite Map Type](06 Satellite map type.png)

Satellite map type

![Terrain Map Type](07 Terrain map type.png)

Terrain map type

Map Details: Traffic, Transit, Cycling, 3D, Globe, Street View, COVID

With the map details layers, Google Maps really starts to show you its depth.

The traffic, transit and cycling layers highlight information relevant to those modes of transport on the map. For example, the traffic layer shows you how busy the roads are in real time with a red to green color grade.

![alt_text](08 With the traffic layer turned on, roads without too much traffic are green, while busy roads are amber and red.png)

With the traffic layer turned on, roads without too much traffic are green, while busy roads are amber and red.

On mobile, you can toggle 3D on and off (where it’s available). Toggled on, this shows you 3D models of buildings and structures when you’re zoomed in.


3D mode can show you how a city really looks to help you orientate yourself – especially around really high buildings.

Most maps flatten the curvature of the earth onto a 2D surface – a process called projection. The globe layer (web only), gives a 3D model of the real global planet instead – naturally, this is only noticeable if you zoom out far enough.

![alt_text](10 Yes, the earth is round..png)

Yes, the earth is round.

The Street View layer shows you where Street View is available on the map.

![alt_text](11 The Street View layer is your gateway into Street View images – just click on any road with the blue line through it to start exploring..png)

The Street View layer is your gateway into Street View images – just click on any road with the blue line through it to start exploring.

Photographs taken at street level and a simple UIallow you to check out new places or just find funny goings on around the world.

![alt_text](12 Explore the real world with street level photography..png)

Explore the real world with street level photography.

The Street View car cameras have covered over ten million miles of road in every continent, plus thousands of landmarks, parks and places of interest – including the International Space Station!

In 2020, Google Maps introduced the COVID-19 Info map details layer. This shows any available local data on COVID-19 infection rates for the areas you’re looking at.

![alt_text](13 See critical COVID-19 information over the map to help you plan safely..png)

See critical COVID-19 information over the map to help you plan safely.

Announcing the new feature, Google Maps said it would help its users to “make more informed decisions about where to go and what to do”.


Explore is the way Google Maps presents all of its business directory, opening hours and other local information. Sometimes Explore elements are integrated into other Google Maps features like Directions as well.

You can use this application to find nearby places of interest like ATMs or grocery stores, as well as checking opening hours and busy times for places you’re planning on going to.

Explore is showing you servers and servers full of geocoded data– but we’ll get onto that later in this chapter.

Google My Maps

Google My Mapsisn’t really a part of Google Maps. Instead, it’s a separate application built on top of Google Maps data. It lets you create custom maps with location markers, directions, measurements and pictures and text notes. You can save and share these from your Google account.

![alt_text](14 Google My Maps lets you build custom maps on top of Google Maps data..png)

Google My Maps lets you build custom maps on top of Google Maps data.

Google My Maps has a lot of everyday uses. For example, you can create a custom map showing a road trip route, share that with your friends, and have them add pictures and places you stopped along the way. You’ll create a digital, shareable, map and scrapbook of your trip.

Saving and annotating all of the lunch spots near your workplace can be a fun activity to share with your team, or just creating and planning the best bike courier delivery routes in your city.

Google Maps Platform

Google Maps also lets other people and companies use its data. The Google Maps Platform is a collection of APIs and SDKs that lets developers embed Google Maps into mobile apps and web pages, or to get information out of Google Maps.

Big companies like Uber and AirBnB rely on Google Maps to power core parts of their business. But Google Maps Platform can be accessed by any developer – and new and innovative Google Maps-based applications come out every year.

Access Advisr combined Google Maps with crowdsourced data on wheelchair accessibility around the world, and got recognized for its creative “mashup” web application.

Google Earth

Google Earth is another separate application that’s been built up from (and in some cases alongside) Google Maps. Tens of millions of individual images covering most of the planet at over 20 levels of zoom – and across a timescale of up to ten years – are combined with a 3D mesh that represents the dimensions of the earth’s surface and the buildings, infrastructure and even animals on top of it.

Satellite and aerial photography images (over 800 billion pixels worth at each zoom level) are selected by computers for the best, crispest look possible – at Google they call this look “springtime everywhere” because of the algorithm’s preference for photographs taken on clear, sunny days.

Google Earth adds educational content, information, Street View and other features over this imagery to make a powerful virtual experience of the entire world.

These features also require a lot more computing power than the more everyday aspects of the web and mobile apps. You can download Google Earth software for free to get the most powerful version on your computer.

Google Earth, like a lot of the features in the main Google Maps apps, performs a second task of cartography (after finding directions) really well: education. Google has said, “Google Maps is for directions, while Google Earth is for getting lost.” But it’s not quite that simple, with lots of educational (and getting lost) elements in Google Maps as well.

What makes Google Maps good both at finding directions and giving rich and valuable information is the solid foundation that it’s built on: vast, constantly growing sets of geocoded data.


Behind these applications are 20 petabytes (that’s 20 million gigabytes) of data. We can think of two streams of data that feed Google Maps: map dataand directory information.

![alt_text](15 The web app_s uncluttered interface.png)

One of many data storage facilities that Google runs to keep all the data that powers its products. (Image source.)

Map data

The map data is all of the information that makes up the maps in Google Maps apps. It’s an enormous database of geocoded data– that is, places referenced in a way that computers can understand and further annotated with useful information.

You could think of Google Maps data as a giant spreadsheet with each square foot of the map area given its own row. As well as latitude and longitude, columns would include other annotations like road or surface type, building type and so on.

This map data is provided by 431 public and private organisations in 43 regions around the world. You can see who the copyright holder is at the bottom of the screen. It’s also bolstered by satellite imagery, Google Maps staff and user contributions through the Local Guides programme (see how this works in the Chapter 3: Using Google Maps).

This map data is computationally processed as a graph. Intersections are represented as nodes, while segments of streets, roads, highways and paths between intersections are represented as edges.

16 Just hit the tab key to flick between controls without using your mouse

All of the geographic data that Google Maps uses is processed as a graph. (Image source.)

For route findingin driving mode, the edges in this graph are also annotated in real time with traffic information. This comes from smartphones with Google Maps installed, and is used by Google Maps to show you congestion points on the road.


Live geocoding – what’s happening to show you real-time traffic updates – is one of the more impressive features of modern weband mobile mapping, but there is another element of Google Maps geocoding that’s mind blowingly complicated once you think about it.

Now known as GTFS (the General Transit Feed Specification), this Google Maps web mappinginnovation started as an experiment in Portland, Oregon and evolved to become the standard formatfor sharing transit information around the world.

City authorities and a Google Maps employee created a formatfor reliably and efficiently storing transit datain 2005, which led to Portland becoming the first area to trial the transit version of Directions.

This formatstored data about journeys, timetables, stops and stations, routes, carriages, operators, step-free access and more – alongside geographic references that computers can understand.

This is a lot of information! And it’s really tricky to put into a format that computers can process efficiently. That’s what was so special about the Portland experiment – the format that Google Maps developed for storing, sharing and processing timetable and station information. This is what would become known as the GTFS (General Transit Feed Specification).

GTFSreliably stored information from train and bus stations, route timetables, station walk times and station timetables in the graph of Google Maps data– as annotations on road segment edges and intersection nodes.

The new file formathelped journey planningservices like Google Maps become everyday stalwarts – helping people to plan multi-modaljourneys across buses, metro lines, trams and boats around the world.

Directory information

As well as this map data, Google Maps is also made up of directory information. Business hours, menus, phone numbers, wheelchair access and much more information is available for countless businesses and public places around the world.

A lot of this data comes via Google My Business, where business owners can upload and edit information about their own store (find out how to claim your business in Chapter 3: Using Google Maps). Google Maps also licenses directory information databases from companies like ThomsonLocal.com.

Finally, directory information is added, amended and verified by members of the voluntary Local Guides program. You can find out how to become a local guide in Chapter 3.

All of this directory information is referred to as geocoded data. It’s information about a specific place, formattedin such a way that it can be processed quickly, efficiently and reliably by computers.

It’s this geocoding that enables features like route findingand local searchto work.


The reason that geocoding is so important is that it packs all of the useful data about places into a formatthat can be stored and processed with computers – that is, mathematically. The mathematical keys that tell computers how to process [data_ **are called algorithms.

These algorithms are the engines that make Google Maps applicationswork with data to do useful things like displaying a map, multi-modal journey planning and local search.


Google Maps now uses vector tile-based rendering algorithms to display map data. Vector tiles are packages of geographic data that can be transferred over the web at low transfer sizes, with more flexibility for browsers to style the map how they want.

Route finding and journey planning

Route finding and journey planning are some of the most complicated things that Google Maps does – in fact, they represent a classic problem in computational complexity theory. To find the best route from A to B, a computer searches along countless deviations of possibilities until it finds the right one – and it has to do it quickly, and often with additional parameters such as avoiding toll roads or departing after a certain time.

There’s a distinction between route finding and journey planning. Route finding is single-modal, it’s for a single means of transport like a car, bicycle or on foot. Journey planning is multi-modal, it involves multiple modes of transport like trains, buses and even planes with different timetables.

To find the fastest route or journey between two points, Google Maps uses packet forwarding algorithms.

In simple route finding, packet forwarding works like this:

  1. The algorithmmakes a packet, a digital representation of you in the graph of map data.
  2. It forwards that packet one node (or intersection) at a time, until it reaches your destination.
  3. Annotations on edges (road segments) give the average trip time along each edge at the time of day as well as real-time traffic information and information about the type of road or highway.
  4. This route is compared with other possible routes to find the fastest one, which is presented to you.

For journey planning, packet forwarding algorithmswork in a similar way, but there is a lot more information to process. As well as the length of time it will take to travel between nodes, journey planning has to take into account first and last departures, transfer times, late services and so on (all of this was made a lot easier with GTFS).

Keep reading to get the most out of all of this – the applications, dataand algorithmsthat make Google Maps what it is.

Written by Ben Pilkington. Published January 27, 2021.