Halloween is an ancient night, older than you may imagine. My earliest record of it is from Celtic and Pagan times. It has been recognised for a long time as a night when the supernatural gap between the living and the dead narrows...
October the 31st is not the only night recognised for this strange and mystical occurrence; the solstice eves in summer and winter are also known for a rare experience when the planes of the living and dead draw closer. Such times were noticed even by Muggles, though it was the foolishness of knowledgeable wizards at the time who let the truth leaked out, and it is unfortunate that Muggles even today have a good knowledge of Halloween.
However, Muggles incorporated Halloween as a holiday and since early times it has developed into a more comical and commercialised day than one of supernatural interest, though the knowledge still - and always will - remains among many Muggles, especially Muggle 'Witches'. At times Muggles have conjured unkind spirits and demons during seances they have no control over.
On such nights as Halloween, things that otherwise could not even be attempted become possible; contact with the dead becomes clearer, and you are more likely to be visited by a spirit of some kind - either a benevolent spirit, who can guide you in your training as a Witch or Wizard, or offer you knowledge about the Plane of the Dead. However, the latter is an extremely rare blessing. Of such great power and importance is the knowledge of the Planes that exist parallel to our own that few spirits wish to divulge it in mortals.
If not by a benevolent, you can just as easily (and more commonly) be visited by a malevolent spirit. These spirits vary in potency, ranging from the very weak yet spiteful, to the extremely strong and dangerous. Such spirits are unfortunately not rare, and usually prey on Muggles or weak Witches and Wizards. So great is the risk during spirit invocation that it is necessary to have a strong Witch or Wizard with you all the time who has the knowledge and power to turn spirits. Having such a person with you will usually discourage an evil spirit from visiting you. However, should you find yourself in a situation where you are confronted with a dangerous spirit, the Patronus Charm is most potent in defending yourself against spirits, and even a weak Patronus can be put to good effect.
Apart from spirit invocation, Halloween is also a good time to practise into the Shadowed Path of Knowledge, the Dark Arts. Such shrouded information is often more generously doled out on Halloween night than any other, and spells are often found more potent on Halloween Night. However, the practise of dangerous spells on Halloween night must be warned against. Some spells are found to have far greater energy on this night, and therefore may have unexpected and highly explosive effects. Always practise with caution - a word of advice that should not be taken into account on Halloween night, but every time you cast a spell.
