What is SQL?
SQL (pronounced "Ess Que Ell" or "Sequel"), commonly expanded to Structured Query Language, is an international standard for querying databases. Read more about it at [http://en.wikipedia.org/wiki/SQL Wikipedia's SQL] entry, and notice the [http://en.wikipedia.org/wiki/SQL#History naming trivia!]
MySQL, is the the most popular Open Source SQL database management system. It's developed, supported, and distributed by MySQL AB. At the core of it, there's an SQL server, but it comes with many access methods, such as the MySQL Client, and various Connectors.
MySQL is pronounced "My Ess Que Ell" ("My S Q L"). But we're friendly people, so we don't get angry if people say "Mysequel".