The base of a jacket is the bottom of the jacket, all the way around the entire jacket. It is usually made of a sturdy fabric, such as canvas or denim, and is often reinforced with stitching or other methods to prevent it from tearing. The jacket base can be plain or decorated with a variety of elements, such as pockets, buttons, or zippers. It can also be made of different materials, such as leather, fur, or wool.

The base of a jacket is an important part of the garment, as it helps to keep the wearer warm and protected. It also helps to give the jacket its shape and structure. The type of base used will vary depending on the style and purpose of the jacket. For example, a winter coat will typically have a thicker, warmer base than a spring jacket.