At the risk of disappointing all the accountants in the room, this is not the State Earnings Related Pensions Scheme.

When you use a search engine such as Google or Yahoo and enter a search term, the results that are returned to you are displayed on a SERP.

It simply stands for Search Engine Results Page. It's just yet another pointless acronymn designed to make you feel like you don't understand the internet. People understand perfectly well if you just use the term "results" or "results page" when talking about search engines.

A SERP usually consists of about 10 links to websites that are most relevant to the search phrase or word that you used. They will usually also contain small advertisements. These are generally placed in a column on the right hand side of the page.

The 10 or so most relevant search results are know as "organic results" where as the advertisements are know as "paid results".

This is a search engine related term. It refers to the number of times a word appears in the the text of your page in relation to other words.

For example if you well coffee machines and wish to be found in search engines under the term "espresso machine" you need to make sure that you espresso machine pages use this term frequently to ensure a high keyword density.

However, beware of over doing it. Write naturally or the search engines may thing you are trying to artificially trying to manipulate your position in their index.