Estimation:tells about the time /duration required to 
complete the testing for the module which includes starting 
from requirement analysis,test case creation,issues 
created,defect report up to Test summary repot.
type of defects:
major->affects the important funtionalityi.e without these 
function we cant proceed further to test further functions.
eg:navigating problem of screen from login page to account 
page in yahoo mail
minor-> funcionalities affected but not independent to 
further requirements.
eg:we can use checkmail option in by click on that 
button.But we could not use that button by using arrow keys
Trivial:funcion is working good but with som minor prolem 
like gui..
eg:checkmail button can be placed wrongly in the screen but 
the purpose of checkmail is operaing corectly.