Which axis defines the primary direction of flex items inside a Flex container?

Related questions

1. What is baseline CSS?
2. What is baseline offset?
3. How do I vertically align in Flexbox?
4. What is reverse flex?
5. Is bootstrap using Flexbox?
6. What is flex column?
7. What is Flex direction in CSS?
8. What does align self mean in CSS?

Tags

1. #direction
2. #container
3. #which
4. #primary
5. #defines
6. #along
7. #items