Hi Harish,
In simple words, It is way to give the person his feedback to the post. like appreciation.
If you like someones post( suggestion or help or anything that you feel he/she posted a very good response that have benefited you or satisfaction to other member's query, then you give a Thump's Up.
and you can give Thump's down for those you feel is relevant to the queries.
It depends on the member to give thump's up or thump's down. also its not necessary.
one member is allowed to give only one karma (either up or down) for every six hours, means you can use it after every 6 hrs.
