What Is MySQL?

Category: Databases · Updated 2026-10-30

MySQL is a free, open-source relational database management system that stores data in structured tables and lets applications query it using SQL (Structured Query Language). It runs as a background server process, typically listening on port 3306, and is one of the most common databases bundled with web hosting plans because platforms such as WordPress, PrestaShop and many PHP applications depend on it. MariaDB is a popular compatible fork that works as a near drop-in replacement on many hosts.

How MySQL organizes data

MySQL stores information in databases, each made up of tables with fixed columns, similar to a spreadsheet with strict rules about what each column can hold. A WordPress site, for example, keeps its posts in one table, its users in another, and its settings in a third, with relationships between tables defined through shared ID columns.

A database is the overall container, usually one per application
A table holds rows of similar records, such as orders or posts
A column defines one field in every row, such as an email address or price
A primary key uniquely identifies each row so other tables can reference it

Where MySQL fits in web hosting

Most shared and managed hosting plans run a MySQL (or MariaDB) server alongside the web server, and give each customer one or more databases managed through a tool like phpMyAdmin. Applications connect to it with a hostname (often localhost), a username, a password and a database name, usually defined in a configuration file such as WordPress's wp-config.php.

-- A basic MySQL command-line session
mysql -u dbuser -p
SHOW DATABASES;
USE my_site_db;
SELECT * FROM wp_posts LIMIT 5;

MySQL vs. other database options

Option	Type	Common use
MySQL	Relational (SQL)	WordPress, PHP apps, general-purpose websites
MariaDB	Relational (SQL), MySQL-compatible fork	Drop-in alternative on many hosting panels
PostgreSQL	Relational (SQL)	Apps needing advanced data types or stricter standards compliance
MongoDB	Non-relational (NoSQL)	Apps storing flexible, document-style data instead of fixed tables

MySQL uses the InnoDB storage engine by default on current versions, which supports transactions and keeps relational data consistent even if a request fails midway through.

Managing a MySQL database on shared hosting

On typical hosting accounts, creating a database, a database user and granting that user access to the database are three separate steps, usually handled through a control panel rather than the command line. Hosts commonly cap the number of simultaneous connections a shared account can open, so a sudden traffic spike that exhausts that limit can produce a "too many connections" error until load drops or the limit is raised.

Frequently asked questions

What is MySQL used for?

MySQL stores and organizes structured data for applications and websites, such as blog posts, product catalogs, user accounts and orders, and lets those applications retrieve or update that data with SQL queries.

Is MySQL free?

Yes, MySQL Community Edition is free and open-source, which is why it is bundled with most shared and managed hosting plans; Oracle also sells commercial editions with extra support and features.

What port does MySQL use?

MySQL listens on port 3306 by default, though many hosting providers block remote access to that port for security and only allow connections from the local server or an approved IP address.

What is the difference between MySQL and MariaDB?

MariaDB is an open-source fork of MySQL created by some of its original developers; it aims to stay compatible with MySQL's SQL syntax and file formats, so most applications built for MySQL run on MariaDB with little or no change.

Do I need to know SQL to use MySQL on shared hosting?

Not necessarily. Most website software like WordPress or PrestaShop generates and runs the needed SQL automatically, though knowing basic SQL helps when troubleshooting or using a tool like phpMyAdmin directly.

How do I back up a MySQL database?

The standard method is the mysqldump command-line tool, which exports a database's structure and data into a single SQL file that can be restored later; many hosting control panels also offer a one-click export option.