Locking

There are two types of locking:

• Internal locking: MySQL performs internal locking within the server itself to manage contention for table contents by multiple sessions
• External locking: MySQL gives the option to client sessions to acquire a table lock explicitly for preventing other sessions from accessing the table

Internal locking: There are mainly two types of locks:

• Row-level locks: The locking is granular to the level of rows. Only the rows that are accessed are locked. This allows simultaneous write access by multiple sessions, making them suitable for multi-user, highly concurrent, and OLTP applications. Only InnoDB supports row-level locks.
• Table-level locks: MySQL uses table-level locking for MyISAM, MEMORY, and MERGE tables, permitting only one session to update those tables at a time. This locking level makes these storage engines more suitable for read-only, read-mostly, or single-user applications. 

Refer to https://dev.mysql.com/doc/refman/8.0/en/internal-locking.html and...