Tissue refers to thin, soft paper designed to absorb moisture, like the tissues you use to wipe your nose when you have a cold or dry your hands in a bathroom. Facial tissues, sometimes called by the brand name Kleenex, are made to be soft and gentle so they don't irritate your skin even after you've used many of them during a bad cold.

The word also means the material that makes up living things. Your body contains different types of tissue: muscle tissue helps you move, nervous tissue carries signals through your brain, and connective tissue holds everything together. Think of tissue as the fabric of your body: just as cloth is made of threads woven together, biological tissue is made of similar cells working together. Heart tissue is different from skin tissue, which is different from bone tissue, but they're all made of cells organized to do specific jobs.

Scientists study tissue under microscopes to understand how bodies work and what goes wrong during illness. Doctors sometimes take a small sample of tissue, called a biopsy, to examine it closely and figure out what's causing a problem.