Attachments are what is bonded on to your teeth in order for your trays to snap in real tight. They are like little "bumps" for lack of a better word. I had some problems eating with them at first. I have had my invisalign for about 5 days now and the eating is getting easier but it does take some getting used to. When your trays are in, you don't feel them at all, it's only when you take them out.

Good luck with your treatment!