Big O Notation: For simplifying understading and measuring of algortihm complexity.
Big O notation means algorithm cannot grow faster than another function. Also, there is Big Omega which means algorithm grows at least as fast as another function and the Big Theta which means algorithm grows exactly as fast as another function
Interpolation Search: Like searching for name in phone book or word in dictionary. Uniform distribution and indexed by key you are using to searh. Instead of starting at the middle (like in binary search) you can decide the starting point based on the key and the knowledge of starting/ending point & the idea of distribution.