What does “O(1) access time” mean?

Question

I have seen this term \"O(1) access time\" used to mean \"quickly\" but I don\'t understand what it means. The other term that I see with it in the same context is \"O(n) ac

Answer 1

It means that the access takes constant time i.e. does not depend on the size of the dataset. O(n) means that the access will depend on the size of the dataset linearly.

The O is also known as big-O.