Scrum is an agile way to manage a project, usually software development. Agile software development with Scrum is often perceived as a methodology; but rather than viewing Scrum as methodology, think of it as a framework for managing a process. Scrum encourages teams to work iteratively and incrementally, through a series of sprints. It involves three roles: Scrum Master, Product Owner, and Development Team.

Extreme Programming (XP) is an agile software development framework that aims to produce higher quality software, and higher quality of life for the development team. XP emphasizes team work. Managers, customers, and developers are all part of a team dedicated to delivering quality software. It advocates frequent releases, customer involvement, feedback, and the use of best practices.

The product backlog is a list of tasks identified by the Scrum team to be completed. It is the single authoritative source for things that a team works on. Unlike traditional project management, it's not a breakdown of the work to do, but a list of all desired changes. Management of it involves adding, changing, and deleting items as well as prioritizing and estimating efforts.

Sprint Retrospective is a meeting that takes place after a Sprint ends, where the team reflects on the past Sprint to identify opportunities for improvements and create a plan for implementing them in the next Sprint. This is a time to reflect on the process and discuss what went well, what didn’t go well, and how things can improve.

Test-Driven Development (TDD) is a software development practice where tests for functionality are written before the actual coding is done. The goal of TDD is to make the code clearer, simple and bug free. It is an iterative process that continues in a short cycle of test-case writing, test execution and code refactoring until the test passes.

Sprint Planning is a critical part of Scrum where the team meets to plan the work to be done during the upcoming Sprint. During the meeting, Product Owner, Scrum Master, and the Development Team collaboratively discuss the goals, backlog items, and a plan for delivering those items. The result is a detailed, agreed upon list of tasks, known as the Sprint backlog, which gives the team a clear view of the work to be done. This process ensures transparency, alignment, and commitment to the defined Sprint goals.

The Daily Scrum (also referred to as a stand-up) is a short, time-boxed meeting that takes place every day during the Sprint. In this meeting, the Scrum team synchronizes their activities and plans for the work to be done in the next 24 hours. The team members share their progress since the last Daily Scrum, what they plan to finish by the next meeting, and any blocks or impediments they are facing. The goal is to improve communication, eliminate any potential barriers, and keep the team focused on the Sprint goals.

A Burndown Chart is a graphical representation used in Scrum to track the remaining work for a project or a Sprint over time. The Y-axis represents the remaining effort while the X-axis shows time. The chart provides a simple and powerful visual to track progress, identify potential issues, and forecast when all tasks are likely to be completed. It encourages transparency and serves as an effective communication tool for the team, Product Owner, Scrum Master, and stakeholders.

User Stories are one of the primary development artifacts for Scrum and Extreme Programming (XP) projects. They are a tool used in Agile development for expressing requirements as a narrative focusing on the user perspective - typically a simple, yet informal sentence that point of view of a user. User stories provide a quick way for developers to understand what users need without having to know every detail. They foster collaboration and focus the team on user's needs leading to a product that delivers the most value to the user.

Pair Programming is a practice of Extreme Programming (XP) where two developers work together on the same code at one workstation. One developer, called the 'driver', writes the code, while the other, the 'navigator', reviews each line of code as it is typed in real-time. The roles are frequently switched for an effective collaborative approach. Pair Programming facilitates knowledge sharing, increases code quality, and reduces the risk of errors making it a highly valuable practice in Agile environments.