Bed bugs are small, reddish-brown, oval-shaped, parasitic insects that subsist off of blood. They can drink blood from birds and mammals, but they like human victims best. Humans offer these voracious insects an all-night buffet and provide fantastic places to hide when they're not feasting. These creatures are also world champion hide and seek players, hiding in cracks in walls, in the folds of sheets, in bed frame crevices, luggage, and anywhere else where you're not likely to find them.
Even just a few years ago, bed bugs were a distant problem - something one encountered in the third world, not here in the United States. In fact, they were almost completely eradicated in the developed world by the 1940s. This is no longer the case, though. Bed bugs are back. And the worst part is, you and your home can get them from almost anywhere.
You can stay home all day and still manage to get bed bugs if you live in a crowded area with high resident turn-overs, like an apartment complex or dorm. These pests can crawl at similar speeds to ladybugs, and they're small enough to sneak under doors and through cracks. If you don't spend all day at home, or if you invite friends over, your odds get worse. Friends can bring these bothersome creatures in on themselves and on their pets. If you travel, especially internationally, bedbugs can hitch a ride on you, your clothes, or your luggage to infest your home.
The only way to be certain that you have bedbugs is to find them. There are other signs to look for, like new bumps or bug bites that appear overnight, blood smears on your sheets, rashes and skin irritation, bed bug feces in the seams of your bedding (small, reddish specks,) and moltings, which are light brown in color. In larger groups, these bugs produce a sickly sweet smell similar to overripe raspberries, which can also lead you to suspect an infestation. Still, ultimately, the only way to be positive you have bedbugs is to find living bugs where they're hiding.