Here are some examples of the jackets to which you could be referring:

A base layer jacket is worn underneath other jackets to provide warmth and insulation. It is typically made of a thin, lightweight material such as merino wool or synthetic fleece. Base layer jackets can be worn in a variety of conditions, from cool to cold weather.

A shell jacket is worn over other layers to protect you from the elements. It is typically made of a durable, water-resistant material such as nylon or polyester. Shell jackets can be worn in a variety of conditions, from light rain to heavy snow.

A puffer jacket is a type of insulated jacket that is typically made of down or synthetic fill. It is very warm and can be worn in cold weather. Puffer jackets are often used for outdoor activities such as skiing or snowboarding.

A parka is a long, heavy jacket that is typically made of a water-resistant material. It is very warm and can be worn in cold weather. Parkas are often used for outdoor activities such as hiking or camping.

The best time to wear a jacket base depends on the weather conditions and the activities you will be doing. If you are going to be in cold weather, you will need to wear a base layer jacket. If you are going to be in wet weather, you will need to wear a shell jacket. If you are going to be doing outdoor activities, you may need to wear a puffer jacket or a parka.