Odd Time Signatures
The majority of songs in most popular music styles are in * time. After this, ^ and ) are the most common. However, occasionally you will encounter odd time signatures such as 
( Pink Floyd’s "Money" is a good example of this), I, 
or U. In Jazz and Fusion, odd time signatures are common, and are becoming increasingly more popular in modern Rock and Metal styles as well, so regardless of the style you play, it is worth learning them. Playing in odd time signatures will also help your timing generally. Shown below is a four bar riff in I time. As the time signature suggests, there are five quarter notes per bar.
The following example is in U time. As the time signature suggests, each eighth note is one beat, so the 16ths are counted as the + (and) part of the beat. E.g. the first four 16th notes in each bar are counted "1 + 2 +" instead of 1e+a.
Some odd time grooves are made up of a combination of two different time signatures. E.g. some grooves can be thought of as a bar of * and a bar of ^. Another time variation is to have a basic time signature such as * with an occasional odd time bar as part of the form. The odd time bar often happens at the end of the progression just before the whole pattern repeats. The following example uses three different time signatures. Take your time with it, and count until you are comfortable with the whole part, then try to just feel it as you play. You need to get to the point where an odd time groove feels as comfortable as a * groove.
