Reginheim

Loki:

Names:	Proto-Germanic: *Laugiz ("Blaze/Flame") Other: Logaþore(?), Logi, Lôgna (Old Saxon), Loke, Loki, Lopt, Loptr, Utgard-Loki
God of:	Wildfire and Mischief
Appearance:	Loki is a Giant who was depicted as a thin man with dark hair and a cloak, sometimes he was also depicted with fiery hair and flames around him.

Loki means "Flame" or "Blaze", he is associated with wildfire and is equally unpredictable, he is a full-blooded Giant (presumably a Fire Giant) and he is called "Lord of the Giants".
Despite his close association with the giants he is often seen as one of the Ansen, the fact that Loki is a Giant also explains his evil nature; sometimes he sides with the gods, and sometimes he sides with the Giants.
Loki is a real deceiver and he is associated with lies, he loves pulling dirty tricks and prefers magic above anything else, he often shapeshifts into a fly, falcon, horse, or other creature, Loki is very intelligent and in the legends it is often he who comes up with a solution for a problem, which are in most cases caused by him anyway.
Loki is often seen as an evil god though the older sources do not depict him as such; it may be possible that many of Loki's evil sides have been made up by later Christian propaganda to be able to equal him to Satan, originally he may have only been a funny trickster with a chaotic and unpredictable nature.

Loki's tricks often create problems though, sometimes Loki is a funny character who likes pulling naughty pranks and other times his actions are purely evil; it is Loki who was responsible for the death of Baldr and it is Loki who fathered the three Giant demons that will destroy the nine worlds at Ragnarök.
A very interesting and funny text to read is the Lokasenna ("Loki's swearing"), a text from the Poetic Edda in which Loki disturbs Ægir's party where all the gods are present, he does this right after Baldr's death and the gods are still angry with him, Bragi asks Loki to behave himself and not to ruin the party but Loki starts insulting the gods and uses the most rude words to make his message clear, eventually Thor arrives at the party and threathens to crush Loki's skull if he doesn't leave, Loki, who knows that Thor is serious chooses to leave:

(From the Poetic Edda, Lokasenna:)

Þórr kvað:

63. Þegi þú, rög vættr,
þér skal minn þrúðhamarr,
Mjöllnir, mál fyrnema:
Hrungnis bani
mun þér í hel koma
fyr nágrindr neðan.

Loki kvað:

64. Kvað ek fyr Ásum,
kvað ek fyr Ása sonum,
þaz mik hvatti hugr,
en fyr þér einum
mun ek út ganga,
þvi at ek veit at þú vegr.

Thor said:

63. Silence, thou impure being!
My mighty hammer,
Mjöllnir, shall stop thy prating.
Hrungnir's bane
shall cast thee down to Hel,
beneath the grating of the dead.

Loki said:

64. I have said before the Æsir,
I have said before the Æsir's sons,
that which my mind suggested:
but for thee alone
will I go out;
because I know that thou wilt fight.

After the arrival of Thor Loki leaves Ægir's hall, the gods allow him to escape because it is considered impolite to fight in the hall of a host, Loki turns himself into a salmon and hides himself in a river, but soon after the party the gods find Loki and tie him to three rocks with the intestines of his son Nari, his other son Narfi becomes a wolf, the gods then place a poinsonous snake above Loki so that the snake's poison will drip on his face, then they leave.
Loki's wife Sigyn stays loyal to him and holds a bowl under the dripping poison to avoid Loki from being harmed, every now and then she has to empty the bowl and then the poison drips on Loki's face for a short time; it was believed that earthquakes were caused by Loki who was twisting in pain because of the poison.
At Ragnarök Loki will escape from the cave and lead the army of the Giants during the battle against the gods, eventually Loki and Heimdall will kill eachother during their last fight.

Loki was never worshipped and there are no signs that he was ever seen as a god or that he received offerings, he is more a being that is associated with unpredictability and chaos and he is a friend and enemy of the gods at the same time, he was mainly known in Scandinavia though his name is mentioned in some legends from the continental Saxon lands and is by some believed to be mentioned in the western Germanic Nordendorff inscription as "Logaþore".