Whether you are a IT Professional or a Developer in Microsoft Technologies; you must have seen the below Level numbering in most of the Microsoft Events / Webcasts.

Sample Levels of Microsoft Webcasts
So, what are these Level Numbers and how does this matter to you? Here is the definition of Webcast Levels, which may help you to choose a webcast based on your Expertise Level.
Level 100 (Introductory): Through technical webcasts, you will be introduced to product and technology features, functions, and benefits. Business webcasts will introduce you to product functionality and include demonstrations of end-user tips. You may also learn how and why to invest in a certain product or technology.
Level 200 (Intermediate): Attendees should have Level 100 knowledge of the product or technology because these webcasts drill down further into a topic than introductory webcasts. These webcasts often include product demonstrations, code samples, best practices, and high-level troubleshooting techniques.
Level 300 (Experienced): These webcasts cover advanced material and assume Level 200 knowledge, an in-depth understanding of features in a real-world environment, and strong coding skills. These webcasts provide you with a detailed technical overview of a subset of product or technology features, covering architecture, performance, migration, deployment, and development.
Level 400 (Advanced/Expert): These webcasts assume a deep level of technical knowledge and experience and a detailed, thorough understanding of the topic. They offer expert-to-expert interaction and coverage of such specialized topics as custom code, scripts, application solution development, and architect infrastructure designs and solutions.
So next time if you plan to share a Webcast/Event with your project team; then you can use the above as a reference.
Reference: Frequently Asked Questions About Microsoft Webcasts