A windbreaker jacket is a lightweight outerwear garment designed to provide protection against wind and light rain. It is usually made of synthetic materials and is of lightweight construction. Windbreakers are designed to resist wind chill and light rain, making them a lighter version of a jacket. They often use elastic waistbands and/or armbands, and a zipper to allow adjustments for the current weather conditions. Windbreakers may offer light to moderate insulating protection, more so than a sweater, but less than an overcoat. They are primarily worn during the warmer seasons when wind or rain are expected, or as part of a layering strategy during colder seasons.

Windbreakers are different from rain jackets in that they are designed to block wind, while rain jackets are constructed with multiple layers of fabric to keep you dry and may also include an insulating layer for warmth. Windbreakers are not waterproof, so they are not ideal for wet weather.

When choosing a windbreaker, it is important to look for lightweight and easily packable polyester or nylon fabrics that make for the best windbreakers. Windbreakers may also include large pockets on the inside or the outside which allows belongings to be covered from weather such as light wind or rain. Brightly colored windbreakers may also be worn by runners as protection from the weather, and as a reflective garment used for safety.

In summary, a windbreaker jacket is a lightweight, synthetic jacket designed to resist wind chill and light rain. It is ideal for dry, breezy days and is primarily worn during the warmer seasons. When choosing a windbreaker, it is important to look for lightweight and easily packable polyester or nylon fabrics.