SQL (Structured Query Language) is a standard programming language used for managing, querying, and manipulating relational databases by performing operations such as retrieval, insertion, updating, and deletion of data.

SQL is the most widely used language for interacting with relational databases. It is composed of different types of commands:

• DDL (Data Definition Language): Defines database structures (e.g., CREATE, ALTER, DROP).
• DML (Data Manipulation Language): Handles data operations (e.g., INSERT, UPDATE, DELETE).
• DQL (Data Query Language): Retrieves data from the database (e.g., SELECT).
• DCL (Data Control Language): Manages permissions (e.g., GRANT, REVOKE).
• TCL (Transaction Control Language): Handles transactions (COMMIT, ROLLBACK).

SQL ensures data consistency and enables users to perform complex queries efficiently. Most modern databases like MySQL, PostgreSQL, and Oracle use SQL for data operations.

Example SQL queries:

-- Creating a table
CREATE TABLE Employees (
    emp_id INT PRIMARY KEY,
    name VARCHAR(100),
    department VARCHAR(50),
    salary DECIMAL(10,2)
);

-- Inserting data
INSERT INTO Employees (emp_id, name, department, salary) 
VALUES (1, 'Alice Smith', 'HR', 50000.00);

-- Retrieving data
SELECT * FROM Employees WHERE department = 'HR';

-- Updating data
UPDATE Employees SET salary = 55000.00 WHERE emp_id = 1;

-- Deleting data
DELETE FROM Employees WHERE emp_id = 1;