First aid kit is a collection of medical supplies and equipment. The contents of the first aid kit are based on the knowledge and experience of the people who put it together. The different first aid requirements of the areas where the first aid kit may be used and the laws or regulations of the given areas vary greatly.

The international standard for first aid kits is to use the ISO first aid graphic symbol (from ISO 7010), which is a white cross on a green background.

First aid kits can be installed in almost any type of container, depending on whether they are manufactured commercially or assembled by individuals. Standard kits are usually placed in durable plastic boxes, cloth bags or wall mounted cabinets. The type of container will vary depending on the purpose, ranging from wallet size to large box size.

It is recommended that all kits be placed in clean, waterproof containers to ensure the safety and sterility of the items. If any item is damaged or out of date, the kit should also be inspected and purchased regularly.

Traditionally, commercially available first aid kits, which can be purchased through regular retail channels, are used only for the treatment of minor injuries. Typical contents include bandages, conventional strength painkillers, gauze and low-level disinfectants.

In each area, vehicles or activities have special first aid kits that may focus on specific risks or concerns related to the activity. For example, first aid kits for ships sold through marine stores may contain seasickness drugs.