Priority- which bug should be solved first
severity-how much the bug affects the system function. we 
can differentaiate depending upon the emergency
critical
medium
low

Smoke Test: 
-----------
When a build is received, a smoke test is run to ascertain 
if the build is stable and it can be considered for further 
testing. 

Smoke testing can be done for testing the stability of any 
interim build.

Smoke testing can be executed for platform qualification 
tests. 

Sanity testing:
--------------- 
Once a new build is obtained with minor revisions, instead 
of doing a through regression, a sanity is performed so as 
to ascertain the build has indeed rectified the issues and 
no further issue has been introduced by the fixes.  Its 
generally a subset of regression testing and a group of 
test cases are executed that are related with the changes 
made to the app.