BL term explained
Black List (BL) is a list of sites the purchase of external links which lowers the position of the promoted site in search engines.
Drawing up black-lists preferably in the case of a promotion by link when the links are purchased automatically in large quantities.
It is well known, many link exchanges provide their clients with special software filters. The user configures a filter and weeds out sites that do not corresponded its chosen strategy of promotion.
Often in the settings of the filters includes the possibility of any addresses of these sites. Use blacklist allows you to quickly configure such filters. In the end, the user receives links only from trust sites.
The selection of sites
Website before inclusion in the blacklist is checked mainly on two parameters. First, the ratio of the number of indexed pages to their total volume of pages. Many indexing pages of the website says about the quality of the site, many not indexed pages says in the search engines indicates about some promblem. If a site contains a hundred pages, but the index fell only ten, the way this site is only to blacklist. Experts argue about what should be the optimal ratio of and opinions different.
Further checked the number of external links on the page. This situation is simpler, because experts seems to be agreed on the optimal number of external links on the page. If the number of links exceeds ten, the site will be logged to blacklist.
In the creation of accurate and informative blacklist very effective through search engines. It is no secret that search engines have maintained their own statistics of bad sites using the filters and sanctions and find problem is not difficult.