How do I exit applications?

[AliWonder]

(Xperia S) I'm still trying to work out how this phone works; there seems to be NO 'exit' button to make sure you have properly exited an application? I looked somewhere on the phone & it seemed to be showing dozens of applications open that I have not even opened & I don't know what they are. Please can someone tell me:

1) How to definitively EXIT an app.

2) Is there a list anywhere of the apps that come installed on the phone, and what they do? I want to uninstall those I am not going to use, but at the moment have no way of knowing even what these apps are for.

Thank you.

[zhuhang]

Once u hit home button, go to running apps and stop them manually.
For a list of apps coming together when u buy,

check "apps > downloaded"
Check also "apps > all" to see ALL including system apps, some can be disabled (4.0.4) and some can be uninstalled.
If u have rooted ur phone, use titanium backup to freeze apps(paid service)
This will disable any system apps that cannot be disabled through "apps>all"

Freezing = disable

[AliWonder]

Thank you. But this is insane - every single time I go into 'applications running' there are DOZENS of things running; most of which I am not using, and some - such as 'playstation' - I have even tried to delete, but it has not worked. I cannot spend hours every day shutting off these applications - there must be some easier way? And why do app's I have dragged into the trash keep appearing a 'running'?? !

[PVV]

You shouldnt worry about many apps running in a background, Android is the OS that manages its resourses by itself, so if you running low on memory it will close unimportant apps automaticaly. However if you are still annoyed by this apps you can install some free taskkiller, it usually comes with the option "close all apps".

P.S. If you dragging an app icon in a trashcan you just remove a shortcut from a work table (same as in Windows) but not removing app rfom the phone completly. To unistall an app go to Settings>Apps, or in Play Market>Settings>My apps and choose "Delete" there.