Bring to a boil in a saucepan until the sugar completely dissolved.
Put about 4 tablespoons in to a glass, add ice and then water. (You may have to play just a bit with the final proportion of syrup or water, but it's really, really good.) Or you can use this for your lemonade based coctails.
The syrup will keep for a week or two in the fridge or it can be frozen in ice cube trays and then removed to zip locks (they don't freeze really hard) and used.