Chords tend to progress naturally to specific other chords. This means that for any given chord, there are a limited number of other chords that can follow. This means that every chord has a specific function, meaning that each chord is endowed with a "built-in" tendency to move in a specific harmonic direction.

The functionality of chords follows directly from the rules of good voice leading, since when you constrain chord tones to move in specific directions (for example, by requiring the 7th to move down one step, or by avoiding parallel fifths), you also restrict the chord options for the next chord.

Restricting the chord options in a progression leads to the possibility of mapping out a limited number of "chord pathways". You can explore some of these pathways by using the following interactive chord wheel, which will allow you to explore a variety of "legitimate" chord progressions.

Start your chord progression with a I (i.e. Tonic) chord.

An interesting aspect to keep in mind when you create a chord progression is that your sequence of chords should build and then resolve tension. The buttons in the chord wheel have been arranged such that their vertical height represents the degree of tension of the chord they denote, as shown by the red arrow.