What is a Jack? As in a playing card?

Jack represents the number 10 in a deck of cards and is considered as one of the high-value cards. Here's what Jacks of all the suits look like in a deck.

A Jack is known to be a high-value card in 13 Card rummy. Jack, along with Queen and King holds 10 points.

The Jack card is counted in the high-value cards list. Cards in each suit is considered from low - Ace, Two......to high value cards - Jack, Queen, King, and Ace again.Ace is one card that is used as lowest and the highest card.

King Queen Jack Ace 

Jack is the prince of the time when the pack of cards where first made 

A Jack is the player

This is a very good question that requires a very good answer.

It is the equivalent of 11. Greater than a 10, less than a Queen.

It is the fourth highest card in poker, behind the Ace, King and Queen. Along with Kings and Queens, it is considered a 'face card' and has a value of ten points in games where the cards are assigned point values, such as blackjack, certain types of Rummy and others.

In Euchre, the Jacks play a special role. Euchre is a trick-taking game that involves calling 'trump', or the high suit for a particular hand. Whatever the trump suit is, the Jack in that suit is the highest-ranking card. The Jack of the other same-colored suit has the second highest rank. These are the right and left bowers. Then follow the A,K,Q 10 in the trump suit (for two players, for two teams totaling four players, the 9s are used as well).

It's the one that comes between the 10 and the Queen.

Don't confuse it with the Joker, which is the two special cards that didn't have suits.

a "ten" in poker