A b-side was originally known as the song on the flipside of a 12" or 7" vinyl single that backed the A-side, but wasn't the song promoted or received the radio play. Today CD singles have b-sides along with remixes, even though ironically CD singles only have one side that is used. With CD singles dying a slow death today, b-sides are becoming a rarer commodity. B-sides were originally used to make a single worth the buyer's money and to get fans to buy the singles along with the album it came from.

B-sides are usually songs that do not appear on the actually album that the A-side appears on, ocassionally it does. The b-side song was usually determined not to fit in with the overall sound of the album or it was considered not good enough to be on the album or just plain leftover tracks, so hence it's usage as a b-side. B-sides have often gotten a reputation of being filler and sub-par, even though a good majority of the time b-sides are better than a lot of the album tracks, and in some cases, better than the A-side.

A blue side is a feeling of emptiness and sadness. An act of hopelessness. It can also be an example of depression.

In Super Smash Bros., the side special move (also commonly called forward B, side B, smash B, or over B) is a special attack performed by pressing the special move button with the control stick held left or right.

Someone you talk to that you really don't care about.

When you get a bag of popcorn at the movies and a piece of popcorn hangs off the side of the bag.

A lacrosse term for when the player has a lacrosse stick inserted into his anus with the net side penetrating first. Though similar, this should not be confused with the term "Stick Side", in which the stick is inserted by the side without the net.

"Side Yat" This definition comes from the saying Side man Meaning: An irrelevant and powerless guy, that shows signs of moist and soggy behaviour.

However with 'Side yat'. This is a girl to which a male counter part has some sort of relationship with, however she is more a piece on the side, or a back up if you will, incase his first yat of choice decides to leave him.
This 'Side yat' does not really mean anything to the man, and is just used as a "little bit on the side".