A Beginners’ Guide to Big O Notation « Rob Bell
Big O notation is used in Computer Science to describe the performance or complexity of an algorithm. Big O specifically describes the worst-case scenario, and can be used to describe the execution time required or the space used (e.g. in memory or on disk) by an algorithm.Plain English Explanation of Big O Notation
I've met too many developers who don't grok big OPlain english explanation of Big O - Stack Overflow
One of the best laypersons explanation of algorithm complexity that I've seen.
Traditional computers can solve problems in polynomial time. Certain things are used in the world because of this. Public Key Cryptography is a prime example. It is computationally hard to find two prime factors of a very large number. If it wasn't, we couldn't use the public key systems we use.
Stack Overflow post about Big O notationPlain english explanation of Big O - Stack Overflow