Here’s Big Web Media’s:
Search Engine Optimization is the process of creating or updating a website to improve the site’s ranking in organic search results, with the objective of increasing the volume of quality traffic. This must be done on-page (site architecture, link structure, content, keywords, title tags, etc.) and off page (link building.)
The most important word in that definition is “process”. SEO is an evolving marketing school of thought; a science and an art. SEO isn’t something you do once, it’s an ongoing series of small adjustments that don’t amount to much individually, but when combined with other optimizations can have a marked impact on both user experience and performance in organic search results.
In Short: SEO requires Time + Education + Resources
That is all nice and well, but how does Search Engine Optimisation really work? In this short 3 video by Matt Cutts, currently head of Google’s Webspam team he shares with us just how.