Over the years I have raised ALOT of dogs, almost too many to count. I am still amazed at how different they are, after all they're indivuduals, each with different personalities, quirks and tempraments. The first 2 years are a rollercoaster ride, full of never ending changes, some good some bad, but all very interesting.
There are numerous developmental stages that puppies go through on their way to adulthood. To help your puppy mature into a confident, well adjusted adult dog it's important to know what these are and be actively involved in helping them through the process.
The following chart is a great resource to help understand a puppies development from birth through age 2.