*Best Match* refers to the name of eBay's updated search engine. This is a proprietary set of processes that it uses to organize available items for the user's search results. This system assigns each listing a score based on a number of different factors and then arranges them with the highest scoring items first. The basic principle is to reward seller behavior based on what the average eBay shopper desires and conversely penalize behavior that shoppers don't like. Simply put, the system ranks best practices and good behavior of all eBay sellers and their listings. Conduct a quick search!
This Best Match system provides buyers with more relevant search results instead of endless pages of similar products from just a few large sellers with high shipping prices. Previously, the sorting was based purely on times and prices, resulting in massive quantities of listings for buyers to sift through. This new search engine is becoming integrating into eBay's system in 2009 as the main search feature, eliminating eBay's classic search by June 2009. It is up to seller now to adjust listing strategies along with customer service to maximize the listing scores to attract the most number of views with the new ranking system.
eBay wants to encourage excellent customer service, conscientious behavior, and sustained buyer interest. The specific algorithm for calculating scores for Best Match have not been publicized, but there are some evident, critical ways to increase listing scores, based on eBay's patent application. Details here.