A culture medium is a substance that provides essential nutrients for the growth and maintenance of microorganisms, cells, or tissues in a laboratory setting. It can be in liquid or solid form and is designed to support the specific needs of the organisms being studied, such as bacteria, fungi, or animal cells. Different types of culture media exist, including agar, which is a solidifying agent, and broth, which is a liquid medium. Researchers use these media to isolate, identify, and study various organisms, making them crucial tools in fields like microbiology, biotechnology, and medical research.