So, what type of process is Android Keyboard? I've recently installed CyanogenMod 11 on my (now very old) LG Optimus 2X. After some tweaking, I managed to make it work much snappier than the original ROM, one of the main things being setting the built-in Minfree Taskkiller preset to Aggressive.

This created a large problem, however - when using some memory-hungry apps (like Viber and Facebook Messenger), the taskkiller seems to kill my keyboard. Basically, in the middle of typing a message, the keyboard simply disappears, only to appear a couple of seconds later and then disappear again soon after.

To fix this, I wanted to tweak the Minfree Taskkiller further so that it wouldn't kill the keyboard so eagerly. It offers the following categories of applications to tweak the threshold for killing apps:


Foreground Applications
Visible Applications
Secondary Server
Hidden Applications
Content Provides
Empty Applications


To which of these does the keyboard process belong to actually?
Some time ego I have written custom android keyboard, and finally Keybaord extend android Service class. 
I.e I think We can say - android is a Hidden Application - a  Service.