It installs straight from your browser and then behaves like any other app — its own icon, full screen, no browser bars. Nothing to download and nothing to keep updated.
Safari only — this is the one Apple makes you do by hand.
Can’t find it? The Share button is the square with an arrow coming out of the top.
Chrome can do this in one tap.
Chrome sometimes offers this itself, as a banner at the bottom of the screen. Either route puts the same app on your home screen.
Chrome or Edge — handy for planning the week at a desk.
Safari on a Mac can’t do this yet — use it as a normal tab there, or add it to your phone instead.
Install it now or later — it works the same in a browser tab while you make up your mind.