Fire:
One of the basic elemental types of Pokemon, Fire-types are noteworthy for being much more energy-oriented than most of their fellow Pokemon. While other Pokemon are mostly physical mass, Fire-types are an energy powerhouse not unlike their Electric brethren, but the constant erratic nature of fire is much harder to contain. As a result, Fire-types heat the air surrounding their bodies to about 90 degrees Farenheight when at rest. Their flames are often just irradiated energy taking that form and are above your average room temperature, but by no means lethal or even particularly dangerous. Fire-types emit a low glow in dark places with or without an open flame, which does light the area around them somewhat but also gives away their position. At high levels, Fire types can also utilize energy from the sun to maintain and augment their energy, utilizing the sun's natural radiation.
In battle their irradiated energy changes quickly however, and Fire-types can emit heat from their attacks that easily burns skin, melts rock, or otherwise does intense external damage to the various matter/energy constructs of Pokemon skin. Fire types themselves are immune to burning, and highly resistant to freezing (though it is not impossible if a limb without an open flame is targeted). Strong fire attacks can easily overpower weaker water attacks, despite the type disadvantage. Most Fire types can swim, however if they have open flames active (rather than irradiating) they will take small amounts of damage. Fire attacks cannot be used effectively underwater or in space (why would you battle in space dummy!), as they require oxygen for combustion. During Rain, any active open flames will emit steam, while irradiated energy will give off no signal of being effected. The Fire-type is not damaged by rain, although obviously their Fire attacks will be greatly reduced in effectiveness.
Summary: Fire STAB; immune to burn, 50% reduction in freeze chance, emit a low glow in dark places, takes additional damage if active open flames are exposed to a water attack. Superior senses in volcanic or brushfire areas.