As mentioned previously, search engine optimization is about optimizing your webpage for certain keywords that you would like to position at. Besides increasing the keywords density of the page, bolding or italicizing the keywords does help in your search engine optimization effort. This is because the indexer, which is one of the components of a search engine, actually rips apart a page into various components and analyze them. These include the title, heading, bold, italic and other style portions of a page. When you bold or italic a word, the indexer will interpret this word as of higher importance and relevance than other words in the same paragraph or statement, thus helping your search engine optimization effort.