These tiny chilies are little, red, and - quite frankly - cute. Deceptive, too. They are piercingly hot, with some sweetness. You can soak them in hot water to soften them, if you wish to remove the seeds and ribs to temper them a little. Just be sure to wear gloves. If you grind them in a propeller grinder, be careful either to do so outside or wait until the dust subsides before you take the lid off. I speak from experience, having scorched my eyes so badly with birdseye dust once that I wept for the better part of 2 hours.
Use them in Thai food, dips, or any spice blend in which you want heat. Grind them if you want your dish very hot, or add them whole to soups or stews and then remove them when the soup is as hot as you'd like.