Reefing is the process of reducing a sailboat's sail area (typically the mainsail) to handle increased wind strength, enhancing stability and maintaining control. It prevents excessive heeling and reduces strain on the rig by lowering the center of pressure. Common methods include slab/jiffy reefing (lowering the sail to new tack/clew points) and roller furling.

Key Aspects of Reefing:
Purpose: To prevent the boat from becoming overpowered, maintaining control, reducing heel, and preventing potential, dangerous "round-ups" in high winds.

When to Reef: As a rule of thumb, it is time to reef when the wind exceeds 20 knots, or when the boat is constantly heeling more than 15-20 degrees.

Types of Systems:
Slab/Jiffy Reefing: Involves lowering the sail slightly and securing it to the boom at new points (tack and clew).

Single-Line Reefing: A, often faster, system using one line to pull down both the luff and leech, often with a pulley system in the boom.

Roller Reefing: Rolling the sail around the boom or a stay, commonly used for the jib.

Reef Points: Small lines or patches on the sail used to secure the excess sail material (the "bunt") to the boom.