Most of us carry several means of starting a fire. I like matches, Bic lighters, and a Windmill lighter, plus firestarter - many people favor lint or cotton balls w/vaseline or something similar. My kit weighs just a little over an ounce - easy weight to carry given how critical fire can be.

Depending on the situation, you might not light many fires, especially if you are staying in one place. Using mostly pine wood fuel, I could easily stoke up last night's fire in the morning without using any matches - this is even easier if you are burning hardwoods. The most important factor is practice and experience, gained before you really, absolutely must ignite a fire.