CRITICAL BUG: This is nothing but a crash...suppose when u

r trying to play a song from media player of MIDI format,or

when a incoming call comes to your mobile when u r testing

a particular feature in your device it may crash.They r

many examples like this.

BLOCK: Unable to boot your device or unable to go back to

previous screen or unable to go to ur main menu when u r

testing particular feature.unable to invoke anything untill

and unless you reboot your device

Major: Unable to funtion or misfunctionality of a

particular feature

Minor: Usually GUI bugs comes under minor bugs. These bugs

wont affect functionality. Example overlapping of letters

in message compose screen.