Inner tubes are normally made of butyl rubber or Latex, they sit inside your tyre and are inflated with pump, they sometimes puncture but are easily replaced. Inner tubes are simple but essential – unless you’re riding with tubeless tyres, you’ll always need an inner tube. Carrying spares is always a good idea, even if you are running tubeless, as a large slash or hole will not seal easily.
Source: https://www.cyclingdeal.com.au/parts/tubes/
