What is evil?
Evil is the word we label a person/action/item/place/feeling, which we cannot understand, it simply does not feel good therefore we refer to it as evil.
Evil is the other end of the universal scales, there to balance everything.
Without evil there is no good.
Mostly it is an idea perpetrated by religion, used as a scare tactic, used to make God seem almighty as he can fight evil, demons and the devil. Belief in him will protect you from all that is evil etc It is a tool to manipulate people, keep them within moral guidelines of what is acceptable character traits and behaviours.
Evil is also an excuse a name given to those who have done something bad and need a reason to explain it away. The devil is in them, so they do evil things.
It is the opposite of what we deem to be "normal".
Now we know that our brains dictate to us what is good and evil, it tells us what is unacceptable behaviour if it is functioning, if it is not then we end up with serial killers and paedophiles...insidious and hideous actions perpetrated on others. If a person has an unsociable abusive upbringing, they too may well grow up acting what we see as evil. To their brains it would be normal, as it is all they have experienced.
Places can feel evil, simply because they make us feel uncomfortable, our hairs will rise up on our necks and arms, there may be a chill, we feel something is not right, we cannot explain this, so yep it must be evil (cannot be a change in magnetic energy or anything like that).
If we know something bad happened in a place then in our minds we begin to feel that place is not good...so evil.
Evil is used for things which we do not want to see or know, things which are so disgusting that it can not be acknowledged as anything else.
It is a word not to be feared.