what is web spam???

I've just started my career few months back as an SMO (Social Media Optimization) and now have become addicted to writing blogs and latests news.
I thought that I have learned a lot in these months till my boss asked about web spams and its types.
Oh.. I could'nt answer very clearly.
But now I can understand that web spams are the ways to manipulate the relevance of the page with the purpose of being indexed by the search engines inappropriately using Black hat techniques.
There are numerous types that I wud like to discuss with you so that you become very clear about it.


There are basically two types of Web Spams:

1. Content Spams : that are content based spams like keyword stuffing ( including excessive keywords into the page to get quickly indexed by the crawler), Hidden or invisible text (keywords added with background font color and tiny font size). Others are meta tags stuffings and cloaking (means having two different pages of a webpage, one for search engine that users can;t see and another for users that search engines do not index.
2. Link spams : these are link based spam that take advantage of the link- based ranking algorithm like link farms that are link communities formed referencing one another as more links means more ranking.Another link spam are hidden links putting links where visitors cannot see them to increase link popularity.