Start at the beginning – product backlog

A product backlog is an ordered list of features or work to be implemented in a product. It could be infinite in length; that is, there could always be new requirements for a product. The product owner is an actual customer or an internal representation thereof (think of an iPad product owner representing many millions of users), maintains, updates, administers, and ranks the product backlog. Based on market research, a product vision statement, industry analytics, technical innovations, or simply ideas to test, the product backlog represents the product owner's most valuable ideas and features for a product.

Note

Once the team has selected, planned, and committed product backlog items to a sprint, the product owner cannot make any changes to those items. However, the product owner is given free reign to change the priority, requirements, and even remove any product backlog item that hasn't been committed and planned in a sprint. This simple game rule...