Cell and tissue culture involves growing cells outside of their natural environment under controlled conditions. It requires a source of cells, a suitable container, growth medium containing nutrients like glucose and amino acids, and control of temperature, pH, and sterilization. Cells can be anchorage-dependent, requiring attachment to grow as a monolayer, or anchorage-independent, growing in suspension. Primary cultures are taken directly from tissue but have a limited lifespan, while continuous cell lines are immortalized and more easily cultured. Cell and tissue culture is useful for gene manipulation, cancer studies, plant tissue culture, and producing pharmaceuticals.