The original story of Hansel and Gretel was written and collected by The Grimm Brothers, who were German academics and authors. They introduced and made popular stories such as Snow White, Sleeping Beauty etc, without them these stories would be unknown to us today.
Plot: Hansel and Gretel are the son and daughter of a poor woodcutter and his wife. They are so poor that the woodcutters wife convinces him to get rid of his children so that there will be more money for them to eat. The children overhear their stepmother’s plan to abandon them in the depths of the woods in the dark, Hansel sneaks out, collecting pebbles to lay a path back to the house the next day. The plan goes ahead and the family walk deep into the forest. The adults leave and return home while the children wait for the sun to rise, when it does they follow the pebbles home to the stepmothers dismay. The next night the children overhear the stepmothers plan to take them deeper into the woods, Hansel tries to go out to collect more pebbles but the door was locked and the key hidden. On their way out the following day, Hansel grabs a piece of bread and leaves a trail of breadcrumbs for him and Gretel to follow back. However, when they get deep enough into the forest and the parents leave, they realise that birds have eaten their breadcrumb trail leaving them alone and stranded. After days of wandering around, starving and tired, they stumble across a large house made out of gingerbread, candy canes, sweets and cakes. Overcome with hunger they begin eating the house and an old woman emerges from the house telling the children there is plenty more more food inside and somewhere to sleep. The next day, Hansel wakes up in a cage in the witches house and Gretel is forced into becoming her slave, they soon find out that she is is a witch who wants to fatten Hansel up to eat. After weeks of Gretel being enslaved and Hansel being fattened up, the witch decides its time to eat him. She prepares a hot oven and while she pokes the fire, Gretel shoves her in. While the witch is burning to death, Gretel frees Hansel and they both take all the gold they can find. A bird shows the children the way home and they live happily ever after living off the money they stole from the witch.
There have been many adaptations of Hansel and Gretel since this one, Hansel and Gretel: Witch Hunters(2013) being the latest in the form of a parody in which the siblings have grown up and are hired to kill witches. The reviews are pretty dire with a rotten tomatoes rating of 15%. There are many other film adaptations including a creepy and surreal TV special directed by Tim Burton and a stoner parody Hansel and Gretel Get Baked.
Hansel and Gretel has also been adapted into a very successful and well rated long running 3 act opera with amazing set design and music. You can find a run down of each act here http://en.wikipedia.org/wiki/Hansel_and_Gretel_(opera)