Why do Android phones have three physical buttons?

This question is simple. Android itself is an open source system. If only one button is set, there will be great restrictions on the mobile phone. An open source system, even a system that dumps SDK for free, will force users to return with one click. Is the menu and home button a thing? Moreover, the design of the software does not allow him to do so. Maybe you will say, like iphone, long press and click, but that's a compromise based on all software. It's like designing an input method for iphone users, but it doesn't support touch screen input and can only use buttons. As we all know, the iphone has no other input keys except the home button. Are you forcing people to buy keyboards? This is obviously unrealistic, and the final result is that the software is abandoned.

Maybe the three buttons are really ugly, but the effect is beyond doubt. Without a menu, many menus can't be opened. If there is no home, many programs can't quit. If you don't return, many softwares can't return to the previous menu. After the iphone enters the menu, there will be a return at the top, which is to replace the entity with a virtual button, but Android is different. After entering, you can only operate by physical keys. If there is no back key and no menu, it will be very troublesome. Things that can be done in one step usually require several steps, even a dozen, or virtual keys can be used instead of three keys, but not all users will install and use them.

This is inevitable. If Android changes its design at this time, it will be useless, because Android is just a system, not a mobile phone manufacturer or a marketer. If the system design is too closed, who will use it? Don't say Android is open source. Once closed, it is useless to open source again. You can only compromise with the public.

But many APADs (pads using android) have only one button. If you don't think the mobile phone looks good, you can buy a smaller APAD.