Riffs

So what exactly is a riff? We can all recognise the sound of a riff, but how to describe them...well the clearest description I've found is "is a short (usually repeating) phrase of music".
Here's a few examples you might have heard...

Here's a couple of more funky examples...

So where to start when writing your own riffs?

• KEEP IT SIMPLE! The most effective riffs work because they are memorable, this is largely because they are simple and rhythm based. Many use a small range of notes but with a funky, syncopated rhythm.
• Many riffs use no more than three or four notes, but often create variety and interest by using big interval jumps i.e. an octave.
• Many riffs are based on scales commonly the: 
• minor pentatonic i.e. A minor pentatonic is A, C, D, E, G
• natural minor i.e. A natural minor is A, B, C, D, E, F, G 
• "modes" (scales based on the major scale) are also used, two common types are:
• D Dorian is D, E, F, G, A, B, C.
• G Mixolydian is G, A, B, C, D, E, F.