What are HTML5 games, and why do they run in your browser?

If you have ever clicked a game link and been playing within seconds, you have used an HTML5 game. The name is a bit loose: it usually means a game built with the web’s own technologies, which every modern browser understands, instead of a program you install.

How they work

A browser can draw graphics, play sound, read your keyboard, mouse or touch screen and keep track of time. Developers combine these abilities using JavaScript, which runs the game’s logic, and either the canvas element for 2D graphics or WebGL for 3D. Larger games are often made in engines such as Unity or Construct, which can export a version that runs in the browser. These exports are made of ordinary files: a small HTML page, a script and one or more data files that hold levels, pictures and sounds.

Why there is nothing to install

The files are downloaded to your browser the first time you open the game and are then kept in a cache, so a second visit is usually much faster. Because the browser runs the game in a restricted environment, it cannot freely read your files or change your system, which is a big reason browser games are considered safer than random downloads.

What limits do they have

Browser games share your device’s memory with every other open tab, and they cannot always use all of a graphics card. Very large 3D games can take a while to load, and a phone with limited memory may struggle. They also need an internet connection the first time you play, although some games continue to work offline once cached.

Tips for a better experience

Keep your browser up to date, as updates regularly improve speed and security.

Close tabs you are not using before starting a large game.

Use full screen if the game offers it; it often runs more smoothly.