What is 'Outliers' by Malcolm Gladwell about?

It is a discussion of the combinations of luck, talent, practice, and privilege that cause certain people to become extraordinary. One of the ideas is that it takes 10,000 hours of practice to become extraordinarily good at something, so people who start practicing a skill young and practice very often get much better at that skill. Some environmental factors figure in, such as access to practice space, the person's age at a crucial time -- for example, most hockey players were born in January -- they were of optimal size when youth teams were formed so they had more practice than other people.