What exactly is Gas lighting?

I saw a post come up on my facebook feed there other day titled You're Not Going Crazy; 15 Signs You're A Victim Of Gaslighting.

A friend of mine posted it and we got onto the topic of what gas lighting is particularly in layman's terms.
I explained this to a friend the other day in a metaphor:

"It's like a game of verbal tennis, but you always seem to lose - every time. Then you're made to feel crazy about trying to play the game."

It was a fruitful conversation in which she came to the understanding that a loved one - or someone she thought was a loved one was gas lighting her.

It got me thinking about all the times I have been gas lighted by people whom I thought were good people, and from others who had also had a similar experience.

For my experiences, I'd bring a concern forward, only to get yelled at, told that I was the one in the wrong, and an apology was never given. If it was, it was half assed with an excuse; the whole I'm sorry but...
It would get the point where I'd rather avoid an individual than walk on egg shells around them for the simple fact that I knew things wouldn't go so well If I slipped up.... And I ALWAYS slipped up. It was always my fault.
I've noticed now that I always take the blame for everything, even if it isn't my fault. I throw myself under the bus for everyone else. I'm scared to hurt people.

If you're not sure, here is a few of the list in the article above that can help determine whether or not this is your experience:

• You frequently second-guess your ability to remember the details of past events.
• You feel confused and disorientated.
• You feel threatened and on-edge, but you don't know why. (I like to call this, "walking on eggshells")
• You feel the need to apologize all the time for what you do or who you are.
• You never quite feel "good enough" and try to live up to the expectations and demands of others, even if they are unreasonable or harm you in some way.

You can see the full list in the link listed above.

Have you ever experienced gas lighting? If so, what was your experience?
Comment below with your thoughts and experiences.

Let's bring light to this conversation.