In some contexts, the term SEM is used exclusively to mean pay per click advertising, particularly in the commercial advertising and marketing communities which have a vested interest in this narrow definition. Such usage excludes the wider search marketing community that is engaged in other forms of SEM such as search engine optimization and search retargeting.
Affiliate Marketing: Affiliate marketing is one of the oldest forms of marketing, and the internet has brought new life to this old stand-by. With affiliate marketing, you promote other people’s products, and you get a commission every time you make a sale or introduce a lead. Many well-known companies like Amazon have affiliate programs that pay out millions of dollars per month to websites that sell their products.