Port 1433 is the default port of SQL Server, and SQL Server service uses two ports: TCP- 1433 and UDP- 1434.
Among them, 1433 is used for SQL Server to provide external services, and 1434 is used to return which TCP/IP port SQL Server uses to the requester.
SQL Server is a relational database management system (DBMS) developed and popularized by Microsoft. Originally developed by Microsoft, Sybase and Ashton-Tate, the first OS/2 version was released in 1988.