Search engine optimization (SEO) is the process of improving the volume or quality of traffic to a web site from search engines via "natural" or un-paid search results as opposed to search engine marketing (SEM) which deals with paid inclusion.

Typically, the earlier (or higher) a site appears in the search results list, the more visitors it will receive from the search engine. SEO may target different kinds of search, including image search, local search, video search and industry-specific vertical search engines. This gives a web site web presence.

Cross-browser refers to the ability for a website, web application, HTML construct or client-side script to support all the web browsers. The term cross-browser is often confused with multi-browser. Multi-browser means something works with several web browsers. Cross-browser means something works with all versions of all browsers to have existed since the web began.