A forgetting curve is a representation of memory retention over a period of time. Based on some early studies conducted by Ebbinghaus, it was shown that the forgetting curved follows a logarithmic curve. Given that there was no attempt to retain it. But how do you retain a memory.
Memories in our brain become more consolidated when we try to recollect it. That is why being tested on new concepts help you remember them more. However, testing yourself right after you learned something doesn’t help. This is where spaced repetition comes into play. The more spaced out the repetitions are more you can retain with a reducing effort every subsequent try.
When we encounter a new experience and we recollect an already existing memory. There are two possibilities that can happen. If the new experience is in agreement with the existing memory our brain consolidates even more. If it is differing, our brain creates a new memory based on the original memory. A representation is shown in the below picture.