At the most basic level, this means you can, as with Lycos, search for sites that contain either any or all of your search terms. InfoSeek and Open Text Index are the only engines that give you proximal operators, which let you search for terms that appear near or next to each other. Using all the tools available can increase the quality of hits dramatically. Most engines help by showing you, at the top of the results page, the words they actually searched for. Remember, you can tell many search engines to look for whole phrases instead of just keywords.
Most engines return hits in order of relevance.
Different search engines use different methods to calculate relevance. InfoSeek ranks hits according to how frequently your search terms appear in the page relative to their frequency in the entire database. Lycos ranks them based on the number of terms found on the page, their proximity to one another, and their position on the page. Most engines also give you some kind of description of the hits. Lycos does this best, giving you a relevance rating, a page description, and a brief abstract of its text.