The 4Ps of Marketing.
http://www.netmba.com/marketing/mix/

Coming into this, I used to think that marketing is the process of making the target market aware of the product/service you are trying to sell. It seems like that is just one of the Ps (Promotion), I would now revise my definition of marketing as "the work done to decide on the right product for the right market and then all the work that is involved in making the consumer aware of the product and getting it into the hands of the consumer.