How does an insulated bag work?

https://www.sannecooler.com/cooler-bag/insulated-lunch-bags-with-logo.html

An insulated bag works by using layers of materials that help maintain the temperature of the contents inside, whether hot or cold. Here's how it operates:

Outer Layer: Typically made from durable fabric like polyester, nylon, or plastic, the outer layer protects the bag from external elements, such as moisture or physical damage.

Insulation Layer: This is the key part of the bag. It consists of a thermal insulation material like foam or reflective aluminum foil. This layer traps air, which slows down the transfer of heat. When you store cold items, the insulation helps keep the cold air in, preventing external warmth from affecting it. For hot items, it works similarly by retaining the heat.

Inner Layer: The inner layer is often made from a material like plastic or aluminum foil that’s easy to clean and resistant to liquids. This layer ensures that spills or condensation don't damage the insulation layer and helps maintain the temperature.

By preventing heat exchange with the external environment, the insulated bag keeps food or drinks at the desired temperature for longer periods. Some bags also have additional features like airtight zippers or seals, further minimizing heat loss or gain.