While there are many components within a cell, the four main ones are:

1. Plasma Membrane: This is the outer boundary of the cell, acting as a selectively permeable barrier that controls what enters and exits the cell.

2. Cytoplasm: This is the gel-like substance that fills the cell, containing various organelles and the cytosol (the fluid portion).

3. DNA (Deoxyribonucleic acid): This is the genetic material of the cell, containing the instructions for building and maintaining the organism.

4. Ribosomes: These are small, complex structures responsible for protein synthesis, following instructions from the DNA.

These four components are fundamental for the cell's structure, function, and survival.