Cell culture involves the growth of cells in vitro under controlled conditions for research and biotechnological applications. The cells may originate from primary cultures or established cell lines, and their maintenance requires strict practices to prevent contamination and ensure viability. Techniques include cryopreservation for long-term storage and methods for analyzing cell proliferation and cytotoxicity. These techniques are applied in vaccine production, biotechnological product development, and the study of cellular mechanisms, while adhering to ethical considerations.