Pilot light systems can be lit with a match or lighter, but it's best to turn the pilot valve to the "off" position to let the gas disperse first. The valve should be moved to "pilot" from the "off" position and then to the "on" position once lit.
Some pilot lights can be hard to reach, especially with bulky lighters. Long matches often used for lighting fireplaces can work well in these systems. Pilot lights use a relatively small amount of gas, but they run constantly, which leads to a steady trickle of wasted gas. This steady draw is noticeable, but pilot lights have one significant advantage many users appreciate: they show that the ignition system is functioning correctly.
To achieve greater efficiency and to assuage homeowners' fears about having an open flame at all times, electrical ignition systems have been developed. These systems have largely supplanted pilot lights on newer heaters. Many ignition systems don't visually indicate when they fire, but many make a slight clicking sound. Since it can be difficult to detect problems related to electrical ignition systems, homeowners may want to fire their system once it's installed so they know what to listen for when troubleshooting their heater.