High card by suit and low card by suit refer to assigning relative values to playing cards of equal rank based on their suit. When suit ranking is applied, the most common conventions from lowest to highest are:

Poker

Most poker games do not rank suits; the ace of clubs is just as good as the ace of spades. However, small issues (such as deciding who deals first) are sometimes resolved by dealing one card to each player. If two players draw cards of the same rank, one way to break the tie is to use an arbitrary hierarchy of suits. The order of suit rank differs by location; for example, the ranking most commonly used in the United States is not the one typically used in Italy. Cards are always compared by rank first, and only then by suit. For example, using the "alphabetical order" of suits, the ace of clubs ranks higher than any king, but lower than the ace of diamonds. High card by suit is used to break ties between poker hands as a regional variance, but more commonly is used in the following situations, as well as various others, based upon the circumstances of the particular game:

Contract bridge

In bridge, suit rank during the bidding phase of the game is by ascending alphabetical order. During the play of the cards, the trump suit is superior to all other suits and the other suits are of equal rank to each other. If there is no trump suit, all suits are of equal rank.