The easiest way to start fire. A lighter is cheap, can be found anywhere and some can even be refilled like tbe Zippo or Butane gas lighter. The 2 most common lighters are the Flame lighter and Jet lighter. Below is a comparison of both lighters.
Flame lighter
Use lighter fluid
Doesn't work well in windy condition
Doesn't burn upside down
Cheaper than jet lighter
Jet lighter
Use butane
Works will in windy condition
Can be burner upside down
Slightly more expensive than flame lighter
Both lighters can be found anywhere and if you have friends who smoke, you do not actually have to carry 1 yourself.