Lock granularity in Database

Multiuser databases use some form of data locking to solve the problems associated with data concurrency, consistency, and integrity. Locks are mechanisms that prevent interaction [which effects the transaction] between transactions accessing the same resource.


Locking granularity is the level and type of information that the lock protects.


Allowed levels depends on the database system you are using. Most common levels are.
1] Database level
2] Table Level
3] Row Level
4] Field Level


REF: Lock Granularity and Hierarchies in SQL Server 2008 R2