### 6.2.9 Reserved Accounts

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 One part of the MySQL installation process is data directory initialization (see [Section 2.10.1, “Initializing the Data Directory”](data-directory-initialization.html)). During data directory initialization, MySQL creates user accounts that should be considered reserved:

* `'root'@'localhost`: Used for administrative purposes. This account has all privileges, is a system account, and can perform any operation.

   Strictly speaking, this account name is not reserved, in the sense that some installations rename the `root` account to something else to avoid exposing a highly privileged account with a well-known name.

* `'mysql.sys'@'localhost'`: Used as the `DEFINER` for [`sys`](sys-schema.html) schema objects. Use of the `mysql.sys` account avoids problems that occur if a DBA renames or removes the `root` account. This account is locked so that it cannot be used for client connections.

* `'mysql.session'@'localhost'`: Used internally by plugins to access the server. This account is locked so that it cannot be used for client connections. The account is a system account.

* `'mysql.infoschema'@'localhost'`: Used as the `DEFINER` for [`INFORMATION_SCHEMA`](information-schema.html) views. Use of the `mysql.infoschema` account avoids problems that occur if a DBA renames or removes the root account. This account is locked so that it cannot be used for client connections.

