Stored procedures in SQL are a group of SQL statements that are stored together in a database and can be reused over and over again. They are similar to user-defined functions (UDFs), but the major difference is that UDFs can be used like any other expression within SQL statements, whereas stored procedures must be invoked using the CALL statement. Stored procedures can perform one or multiple DML operations on the database, and return a value, if any. They can accept input parameters and return results or modify variables and return them, depending on how and where the variable is declared. Stored procedures can be used to consolidate and centralize logic that was originally implemented in applications, and to save time and memory by saving extensive or complex processing that requires execution of several SQL statements into stored procedures, and all applications call the procedures.

Benefits of using stored procedures in SQL include reusability, easy modification, security, low network traffic, and increased performance. Stored procedures can be created in a variety of programming languages, such as SQL, Java, C, or C++, depending on the database system. The syntax to create a stored procedure in SQL is as follows:

CREATE PROCEDURE procedure_name @parameter1 datatype, @parameter2 datatype AS 
BEGIN 
-- SQL statements to be executed 
END 

To execute a stored procedure, the following syntax can be used:

EXEC procedure_name;

Overall, stored procedures in SQL are a powerful tool for managing and reusing SQL code, and can provide significant benefits in terms of performance, security, and code management.