Concurrency control is a technique used in database management systems to ensure that multiple transactions can be processed concurrently without conflicting with each other. It is a critical aspect of database design and implementation, as it helps to ensure the integrity and consistency of data, even when multiple transactions are being processed simultaneously.

There are several concurrency control techniques that can be used in DBMS. These include:

1. Locking: In this technique, a lock is placed on a data object, such as a row or a table, to prevent other transactions from accessing or modifying it until the lock is released. There are different types of locks that can be used, such as shared locks, exclusive locks, and update locks.
2. Timestamp-based concurrency control: In this technique, a timestamp is assigned to each transaction, and transactions are processed in the order of their timestamps. This ensures that transactions that were started earlier are processed before transactions that were started later.
3. Optimistic concurrency control: In this technique, transactions are allowed to proceed without acquiring locks. If a conflict is detected during the commit phase, the transaction is rolled back and the user is asked to retry the transaction.
4. Multiversion concurrency control: In this technique, multiple versions of the same data object are maintained, and transactions are allowed to access and modify the version that was current at the time the transaction started. This allows multiple transactions to access and modify the same data without conflicting with each other.

Concurrency control is an important aspect of database design and implementation, as it helps to ensure the integrity and consistency of data, even when multiple transactions are being processed simultaneously. By using one of these concurrency control techniques, DBMS can ensure that transactions are processed smoothly and without conflicts.