Search Engine: A search engine is a searchable online database of internet resources. It has several components: search engine software, spider software, an index (database), and a relevancy algorithm (rules for ranking). The search engine software consists of a server or a collection of servers dedicated to indexing Internet Web pages, storing the results and returning lists of pages to match user queries. The spidering software constantly crawls the Web collecting Web page data for the index. The index is a database for storing the data. The relevancy algorithm determines how to rank queries.
Specialized Search Engine: A searchable online database of specialized subject resources. There are many. Here is a partial list: Open Source, Law, IRC, Gay, FTP, Employment, Domain Name, Email, Desktop, Canadian, Books, Anonymous, Video, UK, Torrent, Lyrics, Image, Adult.
Meta Search Engine: A server that passes queries on to many search engines and directories, then summarizes the results.
Directory: Unlike search engines, directories are compiled by human beings into a searchable online database.
Pirate Search: An aggregate of general and special search engines, meta search engines, and directories used by researchers to find rare, unique or hidden internet resources. Also used by professional Search Engine Optimizers for tracking how well their web sites rank ( used as an SEO tool ).
The purpose of Silverbeard's Arcadia Web Portal is based on a term known as the "hidden web". The analogy is an iceberg floating in the sea. Only 10% of the iceberg is exposed, the vast 90% is hidden. The largest search engine, Google, may index 10% of the web( which is enormous ). The person using the database may look at the 1st page of a search query without realizing the depth of the internet ocean.
Pirate search( extending the nautical metaphor) is a voyage to find hidden pearls of knowledge.