Being in the market is must for every one and to do well is only a target. Online marketing is consistent field for carrier building. It is some thing like "the show must go on" so it is better now to know about its initial steps.
Whether you want to be an active part of it or you are looking for some agency to sale your product. Online marketing has a broad range of products which can be further divided into may categories and I will put theme here one by one. Soon you guys will see about SEO.