Latent Semantic Indexing
LSI is a methodology involving statistical probability and correlation that helps deducing the semantic distance between words. It’s obviously a complex methodology but can be easily applied to understand the relation between certain words in a paragraph or in a document. This methodology is being used while indexing a page in the search engine’s database.

Link / Hyperlink
Clickable content on a web page usually leads to another page, another site or another part of the same page. The clickable content therefore is said to link to the other page / site / part of the same page. Spiders use links to crawl from one page to the next as they index web sites.

Link Popularity / Linkage
A measure of how "popular" a web page is on the internet as measured by the number of inbound links pointing to your web page. Link popularity is one of the main factors used to help determine search engine rankings.

Log File
Files that are constantly and automatically created and updated on your web server that provide very specific details about the activities taking place on your web site.
This includes referring URLs, IP addresses, pages visited, errors generated, number of unique visitors, total page views, total hits, and much more. Carefully reviewing your log files can provide valuable information about your site's performance and visitors.

Link Exchange
Placing a link to another website on your own site in exchange for a return link back. Also known as reciprocal linking.