Across ages, we the people from the 'Third Rock', have stuck to them candidly; either out of fear or for luck. If we got them right, things seemed to fall in place. It was/is essential to people who feared/fear its effect. To neutralize the fear they believed in it and lived in it. They're a big part of our small life; it's one of those things we , usually, don't put it off until tomorrow.

In earlier centuries, belief in them was magnified beyond limits of emotional and social tolerance. But as times changed we changed, our beliefs changed, and our fears changed. At this point in evolution, our degree of belief in them has been diluted considerably but not vaporized completely. They're parasites, feeding on our fear. They create an emotional turbulence that's beyond pain's pain. We are not talking about ghosts here; maybe we are; some know it as folk beliefs, we know it better as 'Superstitions'.

If you've hawk-eyed around, you'd see that there are superstitions about everything. Superstitions could be linked to myths or prophecies. It could be a belief, a half-belief or a practice with no rational ramification.
Some, who believe in them say, "We have a million experiences in the past that can trade evidence to their belief in certain superstitions."
It could be more appropriately the unconditioning of the mind to disqualify logic and rationale.

It's now our superstition that we respect their choice of fear over freedom, because we live together in a nut shell.

Taking this qualification of the mind further, we may roughly classify superstitions as: religious, cultural, and personal. Every society accumulates certain superstitions as peripheral beliefs. Let's take a birds-eye-view, of some superstitions:

Source: Little giant Encyclopedia of Superstitions.

Black cat Superstitions:
It's good luck to be gifted a Black Cat
It's bad luck if a Black Cat crosses your path.

Broken Mirror:
Breaking a Mirror brings seven years of bad luck, unless you burry the broken pieces of the mirror or thow them in a fast flowing stream.

Ladder:
Walking beneath a ladder brings bad luck.
To dispel this effect you need to walk backwards through the ladder or make a wish while still under the ladder or cross your fingers until you see a dog or spit on your shoe and don't look at it until it's dry.

Love letters:
Unlucky to post a love letter on December 25 or February 29 or September 1.

IRON:
Finding pieces of Iron is lucky.

Milk:
Spilling milk is considered unlucky in most places except Ireland, because according to them milk is the favourite drink of the fairies and fairies don't harm.

Shoes:
It's unlucky to walk in one shoe.

Warders of Evil:
Green chilies tied one below the other under a Lemon which is tied at the entrance of a House or shop.-wards off evil
A horse shoe magnet at the entrance.-good luck and warder of evil

Underwear:
Mending underwear while still wearing it - is unlucky. Is this superstition or underwear fact?

These were some of the superstitions believed across the world, a statutory warning again: Don't follow them or believe in them just because you've read them here - could be unlucky.

Even in so-called modern times, in a day when objective evidence is highly valued, there are few people who would not, if pressed, admit to cherishing secretly one or two irrational beliefs or superstitions.

Cutting the humor, there's more to learn about folklore and popular cultures from these ancient and recent: beliefs, signs, omens, taboos and superstitions.
There are a whole lot of civilizations to learn from these superstitions. Marketers can analyze buyer psychology and behaviours by studying them carefully.

Wow, this key board really keeps me going on and on, I guess it's lucky!!!