What is sleep mode and what happens to an Android phone whn you put it to sleep

So my questions are just like the title says: What is sleep phone and what does your Android do when you put it to sleep. Do the apps keep running in the background or is there no activity? If I want to improve my battery life should I remember to turn off my apps before I put the phone to sleep
?

I guess its *pause*ing the apps? but im not sure! What sleep mode do you mean anyway? Just turning the screen off?

If you really want to save battery, activate flight mode. 2-3% battery / 8 hours

-----
Port of Call <--!--> Youtube

If you're just talking about when the lock screen is on then I'm pretty sure most apps still keep running unless they are set to turn off so it might nto be a bad idea to make sure that all apps are shut down with a task killer or something similar. There is supposedly a deep sleep mode on most Android phones that turn most app function off but I don't know when that is engaged.

Deep sleep kicks in after the phone hasn't been used for awhile though the amount of time is different for each phone. Basiclly all functions are shut down like Wifi, GPS, and even CPU activity to save on battery power.