Server roles are defined at the server level and exist outside of users databases. There are only fixed server roles, so you cannot add, delete or modify server role. You can only add users as a member of the server roles.There are seven fixed server roles:sysadmin serveradmin setupadmin securityadmin processadmin dbcreator diskadmin

SQL Server provides several roles for security

Members of the securityadmin fixed server role manage logins and their properties. They can GRANT, DENY, and REVOKE server-level permissions. They can also GRANT, DENY, and REVOKE database-level permissions if they have access to a database. Additionally, they can reset passwords for SQL Server logins

A server role is a set of software programs that, when they are installed and properly configured, lets a computer perform a specific function for multiple users or other computers within a network. Generally, roles share the following characteristics. They describe the primary function, purpose, or use of a computer.

A server role is a set of software programs that, when they are installed and properly configured, lets a computer perform a specific function for multiple users or other computers within a network. Generally, roles share the following characteristics. They describe the primary function, purpose, or use of a computer.

A server role is pre-defined by SQL Server. It possesses a pre-defined set of rights.