Technical details Main article: Search engine optimization Crawlers rely upon keyword placement within the text of an article, and typically disregard images.[44] Text appearing in several key locations (such as the <title> and <meta> tags of the page's code) gets special attention because search engines compare information found there with other pages to determine relevance. SEO copywriters also strive for unique written content on the page, distinguishing it from similar pages competing for placement in the search results. Other factors that determine relevance during a search are the page's keyword density, the placement of the keywords, and the number of links to and from the page from other pages. Professional role SEO copywriting is most often one of the various jobs of a copywriter. However, there are freelance copywriters who hire out their services solely for SEO, agencies and firms that specialize in SEO (including SEO copywriting), and copywriting agencies that offer SEO copywriting as part of comprehensive writing and editing services. A freelance SEO copywriter will work with a client to determine the appropriate keywords needed to promote the client's business. Online keyword research tools are then used to gather a list of potential phrases.