It's true. Everybody loves a balloon - especially when twisted into familiar objects and animals. The art of creating things from balloons is called twisting.
The most popular type of balloon for twisting is called a 260. The number refers to the size of the balloon when fully inflated. The 2 means it is about 2 inches wide and the 60 means it is about 60 inches long. A 321 (also called a bee body) is 3 inches wide and 21 inches long when fully inflated. A 350 is 3 inches wide and 50 inches long when fully inflated. The 260s are the most popular.
Keep your balloons in a cool, dry, and dark place. They will last longer and will be less likely to break when you start using them. Many twisters keep their balloon stash in a closet or even the refrigerator.
Blowing a 260 up with your mouth is just plain dangerous. It is much safer and more efficient to use a balloon pump. Hand-pumps are sold at most magic or supply stores, but more expensive electric pumps are also available. If you are creative, you can also use a bicycle pump.