What are MySQL Storage Engines? Name the most common ones.

Storage engines determine how MySQL stores and retrieves data.

Common engines:
• InnoDB: Default, supports transactions, foreign keys, row-level locking
• MyISAM: Fast reads, table-level locking, no transactions
• MEMORY: Stores data in RAM, very fast but volatile
• ARCHIVE: Compressed storage for archival data

Example:
CREATE TABLE users (...) ENGINE=InnoDB;
ALTER TABLE logs ENGINE=MyISAM;