A whip is a political party official who serves as the party's "enforcer" within the legislative assembly or house of parliament.
Parties appoint a senior member of their House contingent to issue whips; this person is known as the Chief Whip, and he or she is aided by additional Whips.
The British legislative system gave India the notion of the whip.
(Note: In parliamentary jargon, a whip is also a formal order requiring party members to be present for an important vote or to vote in a specific way.)
Whips' function:
They make every effort to guarantee that their fellow legislators attend voting sessions and vote in accordance with their political party's official policy.
What happens if you don't obey a whip:
If a legislator disobeys the party whip, she or he may face disqualification unless the number of parliamentarians opposing the whip is 2/3rds of the party's strength in the house. The Speaker of the House decides on disqualification.
Whip's limitations:
Whips cannot order a Member of Parliament (MP) or Member of the Legislative Assembly (MLA) to vote a certain way in certain circumstances, such as presidential elections.
The party issues three different types of whips:
A single-line whip is used to notify members of a political party about a vote. It permits a member to vote no if they do not agree with the party position.
Two-line whip: Issued to ensure that all members of the House are present at the time of voting.
Members are given a three-line whip instructing them to vote in accordance with the party line.