Hair coloring - is it good?

I had a good hair color until my college life after that some started looking grey, when i refered, i got advice to color my hair and there are a lot of hair coloring products from a huge number of companies and the cost is also verymuch affordable.

please suggest me will it worth. 

homie wrote I understand the uses, but is the thing harmful for our hair. I mean by personal experiences I know that gel is , but is hair color harmful too? Got to have answer.

Yes, it is harmful especially if your not following the instructions provided by the manufacturers or if you over-process it. If hair dye will stay longer than the instruction given, usually it allows pigment to penetrate to hair shaft. By leaving it too long or by applying too much heat, hair cuticle will not settle down again after coloring. Then, in that case, hair is damaged because the cuticle being lifted will allow the moisture to escape. Moreover, this will allow the hair to become brittle and breakable.