A disk is divided into blocks. Each block is usually 4KB.

In SimpleDB, each file contains a number of blocks, and each block is identified by <filename, block number>.

The main memory is divided into pages. The size of a page is the same as the size of a block.

A buffer manager uses a number of pages for buffering. Each page used by the buffer manager is called a buffer page (or just buffer for short), and all the buffer pages together are referred to as a buffer pool.

A block on disk must be loaded into a page (or a buffer page if a buffer manager is used) before the data can be accessed.