1.) There are 4 types of development. Physical development covers the learning of the ability to walk. It also encompasses all muscle development, and the idea that the person generally becomes more physically efficient over time.
Cognitive development deals with the development of a way to think. For example, an infant tends to over generalize information. If he sees an animal and is told that it is a dog, any furry animal with 4 legs and a tale will be considered a dog. As cognitive development progresses, a person learns to be specific. We also build a sense of problem solving.
Personal development refers to the changes in an individual's personality. As time progresses, and people learn new information, they develop their own opinions. Fact becomes their own knowledge and not just what their parent's tell them.
Social development is the maturing of a person's ability to socialize. They build up ways to relate to others. They find ways to make friends or to accomplish group goals. For example, children meeting at a playground, and becoming "best friends".
These types of development are governed by certain principles, which are accepted throughout the psychology field.
First, people develop at different rates. Also some people will develop only certain types of development quickly, while being slower at others. For an example, look to any nursery school class. It is a virtual melting pot of development. Some children may due exceptionally well at physical activities, while doing badly at anything that requires thinking, or vice versa.
Secondly, there is a basic order to development. Children generally crawl before learning to walk. A child must master basic functions before going on to more advanced situations.
Lastly, development takes place over time. Information must be gathered and proce