Tissue culture or cell culture is a way to grow cells in a laboratory. Cells are taken, and put into in a flask or Petri dish. They are grown on a growth medium, sometimes an agar plate. The cells divide, and can be treated in various ways. This is done for a number of purposes: 
- Growing bacteria or fungi for experiments or for identification. An example would be growing bacteria to see what antibiotics they are resistant to.
- Growing cells of plants or animals for various experimental purposes.