Baz Chaz said:Ordinary granulated sugar.
For 23 ltr brew anywhere between 60g (my lowest) to 120g (far too fizzy for me) thats for batch priming bottles.
if you want to prime individual bottles, between half a level teaspoon and a level teaspoon per 500ml bottle.
Once primed keep in warm for a week, then into cool for a couple of weeks (longer is better)