MySQL stores the data behind WordPress, shops and most web applications. On hosting servers it (or its drop-in sibling MariaDB) runs as one service shared by all accounts, each with its own databases and users.
Because everything depends on it, database trouble looks like “the whole server is broken”: crashed tables break single sites silently, connection floods exhaust limits, slow queries drag the disk. The classic health checks — crashed tables, connection counters, slow-query log — catch each of these early.
Frequently asked questions
MySQL or MariaDB — which do I have?
Many panel servers actually run MariaDB under the mysql service name. mysql --version tells you; functionally they are administered the same way.
What is a “crashed table”?
A table (typically MyISAM) corrupted by an interrupted write. The site using it errors out until the table is repaired — detection plus one-click repair is the standard cure.