What is the framing effect in economics?

Because of the framing effect, the way information is presented to us influences how attractive a proposition is.

Suppose you are considering joining a gym. A membership at £500 per year sounds like a considerable investment and might prevent you from signing up immediately. However, if they tell you it costs just £1.37 per day and emphasize that this is less than the cost of a cup of coffee, you might think it’s a great offer, even though in reality both offers cost you the same.