I have basal cell skin cancer, what will happen during Mohs surgery?

DEAR DOCTOR K: I have basal cell skin cancer on my face and am scheduled to have Mohs surgery. Can you describe what will happen during the procedure?
DEAR READER: Skin cancer is the most common cancer in the United States. Basal cell cancer is a very slow-growing type of skin cancer. It is unlikely to spread to other parts of the body, and therefore is rarely life-threatening. The most common cause of basal cell cancer is damage from sun exposure. Basal cell carcinoma begins in basal cells, which are located deep in the skin. When these basal cells turn cancerous, they invade surrounding tissues, spreading downward and outward below the skin's surface.