Launch Services
Launch Services is a mechanism in OS X which enables the user to specify a preferred application for a certain file type or
which web browser to open url's in. From a programming point of view Launch Services is an API where the developer have the
possibly to register both file types and declare which file types an application supports.
By resetting Launch Services, problems with applications, file types and icons can be corrected.
Mail's Envelope Index
Mail application uses the (SQLite) Envelope Index database to index and search messages. By rebuilding this database, issues concerning messages that appear incomplete or are missing can be corrected. This feature may also improve Mail's performance.
Locate
Locate is a nifty Unix tool available for use in the Terminal or preferred shell. In many ways locate is similar to Spotlight. Both are intended to make you find what you look for. One fundamental difference between locate and Spotlight is that locate searches a pre-index database. The result is strikingly fast search but with the limitation that recent changes might not be in the index and therefore will not be in the query results.
Whatis databases
Whatis is a common Unix tool which provides a way to get super fast and concise help. For example the command whatis cd returns: - Change working directory. Whatis is an excellent tool to find out what a Unix program does.