MarkSheet is a free, comprehensive educational resource designed to teach beginners and designers how to build for the web from the ground up. Created by Jeremy Thomas, it offers a structured, 50-lesson path through the core technologies of modern web development.

The main features of this tool include:

• Comprehensive 50-Lesson Curriculum: The course is organized into 4 sections and 9 chapters, providing a clear and methodical deep dive into web fundamentals.

• Foundation for Absolute Beginners: It begins with essential context on the Internet, the World Wide Web, and how browsers function, ensuring students understand the environment they are building for.

• Core HTML 5 Mastery: A dedicated 13-lesson section covers everything from syntax and semantics to forms and document structure, specifically designed for those ready to start coding immediately.

• In-Depth CSS 3 Training: With 29 lessons, this extensive section teaches how to define style and layout, covering the Box Model, positioning, responsiveness, and advanced animations or transforms.

• Advanced Styling with Sass: For developers looking for more efficient workflows, the tutorial includes lessons on Sass variables, nesting, mixins, and inheritance.

• Step-by-Step Ebook Resource: The creator also offers a companion ebook, "Learn CSS in 44 minutes," which provides a step-by-step guide to building a personal webpage from scratch.

• Open and Accessible Philosophy: MarkSheet is completely free, licensed under Creative Commons, and its underlying source code is open-sourced under the MIT license.