My signature site has what I feel is just the right amount of information to get started in understanding Bitcoin.
There are Bitcoin topics that can go far beyond most people's understanding or desire to learn, such as when we start talking about Merkle trees, digital signature algorithms, hexadecimal math, or subjects that require college-level statistics.
If you have a particular topic you would like to investigate further, you can start at
https://en.bitcoin.it/wiki/Category:Technical