What do the colours in a plug mean?

Brown is live, blue is neutral and the green is the earth.

This can be remembered using the following mnemonics:

Brown is live and you'll be burnt brown if you touch it.

The brown wire is live and you'll be burnt brown if you touch it.

Blue is the colour of water and the pH of water is neutral.

The blue wire is neutral as is the pH of water.

Green grass grows on the earth.

The green wire is earth as green grass grows on the earth.