http://sqlines.com/mysql/auto_increment

-- Define a table with an auto-increment column (id starts at 100)
CREATE TABLE airlines
(
id INT AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(90)
)
AUTO_INCREMENT = 100;

-- Insert a row, ID will be automatically generated
INSERT INTO airlines (name) VALUES ('United Airlines');

-- Get generated ID
SELECT LAST_INSERT_ID();
-- Returns: 100

Overview:

Start Value Default is 1
Increment Always 1
How to Generate IDs Omit the AUTO_INCREMENT column in INSERT, or specify NULL or 0
Explicit ID Insert
Restrictions Only one AUTO_INCREMENT column per table
Primary key or unique must be specified
DEFAULT is not allowed
Last ID LAST_INSERT_ID returns the last value inserted in the current session
LAST_INSERT_ID returns ID for the first successfully inserted row in multi-row INSERT
Gaps If a value larger than the current max ID value is explicitly inserted,
then new IDs with start from this value + 1
Restart (Reset) ALTER TABLE table_name AUTO_INCREMENT = new_start_value;
Version: MySQL 5.6

MySQL AUTO_INCREMENT Details
To generate a ID value, you can omit the auto-increment column in INSERT statement, or specify NULL or 0 value explicitly:

-- Omit auto-increment column
INSERT INTO airlines (name) VALUES ('Delta');

-- Specify NULL or 0
INSERT INTO airlines VALUES (NULL, 'Southwest');
INSERT INTO airlines VALUES (0, 'American Airlines');
Make a Gap
You can insert an ID value explicitly, then MySQL will generate new IDs starting from it adding 1:

INSERT INTO airlines VALUES (200, 'Lufthansa');

INSERT INTO airlines (name) VALUES ('British Airways'); -- id 201 is assigned
You can still insert inside the gap using ID less than the current maximum ID, but this does not affect ID that will be used for other rows:

INSERT INTO airlines VALUES (150, 'Air France'); -- id 150 inserted

INSERT INTO airlines (name) VALUES ('KLM'); -- id 202 is assigned