Lighters are probably the easiest way to make a fire. They are compact, some are good for thousands of lights, and are still cheap. They generally come in three types: disposable, Zippo, and butane.
Types of Lighters
Disposable lighters, generally Bic brand, are highly reliable, good for approximately 3,000 lights, and are cheap. They can be had for less than a dollar apiece and their fluid will not leak out when not in use.
Zippos lighters are durable, refillable, and will stay lit without user intervention. Their disadvantage, however, is that the fluid evaporates out of them regardless of whether or not they are in use. They are also significantly more expensive than other types of lighters.
Butane lighters are reliable, lightweight, wind resistant, refillable, and burn at much higher temperatures making them useful for tasks other than starting fires. A quality lighter is generally going to be more expensive than other types, but they offer many advantages. Due to their higher burn temperatures they also have a tendency to destroy volatile tiner, so they are often used to light kindling directly.