What is fragmentation as used in the topic of database management systems?

Fragmentation in database management systems refers to the division of a database into smaller parts or fragments. This can occur in various ways, such as horizontal fragmentation (dividing rows of a table), vertical fragmentation (dividing columns of a table), or mixed fragmentation (a combination of horizontal and vertical fragmentation). Fragmentation can help improve performance by distributing data across multiple servers or storage devices, but it can also complicate data retrieval and maintenance.