The SQL Server 2005 Buffer Pool
The Buffer Pool is the memory space that SQL Server uses. By default, SQL Server 2005 manages memory dynamically for your database. SQL Server 2005 does not make changes directly to data files - making changes directly to datafiles can be very resource intensive - especially in an OLTP environment. Changes are made instead in memory and written to disk in batches. The buffer pool also contains an area called the procedure cache where execution plans for frequently executed queries are stored.