The assigning of keywords or phrases to pieces of online information (eg, a blog post, a web page or image) in order that it can be categorised effectively. Metadata tags are be used for many purposes including filtering and displaying content within a webpage and providing users with tailored content based on their predetermined selections.

Metadata tags are read by search engines and can determine the order in which results are displayed as well as the description of a search result.

See also:
Search engine ranking
Search engine marketing (SEM)
Cost per acquisition (CPA)
Cost per click (CPC)
Reciprocal links
Ad rotation
Ad impression
Behavioural Targeting
Contextual Marketing
RSS
E-Marketing
User Session
Deep Linking