Can anybody explain me about the tags ........

Adding tags when you create a discussion can be very useful, because they are used when another member searches for a particular subject to respond to. Therefore, if the tags accurately relate to the subject matter, then it is easier for other members to find your discussion and reply to it. This works in the same way that a search engine will use keywords to find appropriate websites. A good amount of responses to your discussion will certainly help your earnings, so it is important to select the tags carefully.

tag is just one word from which the category of discussion could be known. when u discuss about comoputer then u can use tag like computer, technology or any other similar computer related objects. on the basis of the tag u given to your discussion, u can get better idea about the contents of the discussion. u can decide whether discussion is healthy or not or of any interest. i do not have any idea regarding earnings out of tag. u can skip the tag but i would prefer to use tag for any discussion.

i have completed more than 2700 posts but untill i could not stand what exactly is tag

for my own, understanding, tag will help identify certain discussion..just like for example you are searching for something in the internet you can only type one word and then it will lead you to several topics which pertains to the word you are searching...It is useful but you can also skip to it..I guess it doesnt add to your points.