A computer bug is an error, flaw, mistake, failure, or 
fault in a computer program that prevents it from working 
correctly or produces an incorrect result.

If the system is not performing as per the requirements it 
is a bug.

If there is any mistake during coding that is called as 
DEFECT and if this Defect is identified by the tester than 
it is called a BUG.

while test whatever comes defect those are called bug.its 
not a error but put s in suspension or doutful status due 
to some are high difference between actual output or 
exepected output

While test what ever comes defect  those are called bug 
it s not a error but put in suspenssion doutfull status.due 
to some or high diferrence between actual output or 
expected output
A tester find the bug.unexpected behaviour in the 
application is called bug.

Error: A mistake in a coding is called error.

Defect: due to errors in coding testing engineers getting 
mismatches of our app. build this is defect or issue

Bug: these defects or issues are accepted by the devolopers 
to be solve then it is called Bug

variance in expected and actual result according to 
specification called bug