Membership operators are used to check whether a value is present in a sequence or not.

The result of a membership operation is always a Boolean value:

• True
• False

Operator	Meaning
in	Returns True if the value is present.
not in	Returns True if the value is not present.

Membership operators can be used with:

• Strings
• Lists
• Tuples
• Sets
• Dictionaries

The in operator checks whether a value exists in a sequence.

The character 'p' is present in the string, so the result is True.

The character 'z' is not present, so the result is False.

For dictionaries, membership operators check keys only.

Key	Value
100	durga
200	ravi

The value 100 is a key, so the result is True.

The value "durga" is not a key; it is a value, so the result is False.

The not in operator checks whether a value is absent from a sequence.

Dictionary membership operators check only keys.

Since "python" is a value and not a key, the result is True.

For strings, membership operators check whether a substring exists.

• Membership operators check whether a value exists in a sequence.
• The result is always True or False.
• Dictionary membership operators check only keys.
• Membership operators work with strings, lists, tuples, sets, and dictionaries.

Membership operators are commonly used in:

• Login systems
• Search operations
• Validation
• Filtering
• Permission checking

Usage	Example
Login Validation	Username check
Search	Word search
Access Control	Permission validation

Operator	Meaning
in	Checks whether a value exists.
not in	Checks whether a value does not exist.

Operator	Purpose
in	Checks whether a value is present.
not in	Checks whether a value is absent.