A trademark is any unique statement related to a product or service that differentiates it from others. This statement could be a word, slogan, photograph, logo, graphic, colour combination, sound or even smell.
A registered trademark has 10 years of validity. After that it required renewal. You do not need to worry if you forget to renew it as you will receive a past notice at your registered office about the renewal of your trademark. Usually, companies forget to renew their trademark. So, the Registrar informs them regarding the same 6 months before determination. Still, if there is no action from your side, then Registrar issues a statement which says that your trademark would be removed from Trade Marks Journal. It is a very long process and takes at least 6-12 months after expiration. So before that, you can renew it by just paying the amount of fine to the department.