docs/Learn/Accessibility/Mobile)
    8. [ Assessment: Accessibility troubleshooting ](/en-US/docs/Learn/Accessibility/Accessibility_troubleshooting)
  23. [ **Performance â Making websites fast and responsive** ](/en-US/docs/Learn/Performance)
  24. Performance guides 
    1. [ Web performance ](/en-US/docs/Learn/Performance)
    2. [ The "why" of web performance ](/en-US/docs/Learn/Performance/why_web_performance)
    3. [ What is web performance? ](/en-US/docs/Learn/Performance/What_is_web_performance)
    4. [ Perceived performance ](/en-US/docs/Learn/Performance/Perceived_performance)
    5. [ Measuring performance ](/en-US/docs/Learn/Performance/Measuring_performance)
    6. [ Multimedia: Images ](/en-US/docs/Learn/Performance/Multimedia)
    7. [ Multimedia: video ](/en-US/docs/Learn/Performance/video)
    8. [ JavaScript performance optimization ](/en-US/docs/Learn/Performance/JavaScript)
    9. [ HTML performance optimization ](/en-US/docs/Learn/Performance/HTML)
    10. [ CSS performance optimization ](/en-US/docs/Learn/Performance/CSS)
    11. [ The business case for web performance ](/en-US/docs/Learn/Performance/business_case_for_performance)
  25. [ **MathML â Writing mathematics with MathML** ](/en-US/docs/Learn/MathML)
  26. MathML first steps 
    1. [ MathML first steps ](/en-US/docs/Learn/MathML/First_steps)
    2. [ Getting started with MathML ](/en-US/docs/Learn/MathML/First_steps/Getting_started)
    3. [ MathML Text Containers ](/en-US/docs/Learn/MathML/First_steps/Text_containers)
    4. [ MathML fractions and roots ](/en-US/docs/Learn/MathML/First_steps/Fractions_and_roots)
    5. [ MathML scripted elements ](/en-US/docs/Learn/MathML/First_steps/Scripts)
    6. [ MathML tables ](/en-US/docs/Learn/MathML/First_steps/Tables)
    7. [ Three famous mathematical formulas ](/en-US/docs/Learn/MathML/First_steps/Three_famous_mathematical_formulas)
  27. [ **Games â Developing games for the web** ](/en-US/docs/Learn/../Games)
  28. Guides and tutorials 
    1. [ Introduction to game development for the Web ](/en-US/docs/Games/Introduction)
    2. [ Techniques for game development ](/en-US/docs/Games/Techniques)
    3. [ Tutorials ](/en-US/docs/Games/Tutorials)
    4. [ Publishing games ](/en-US/docs/Games/Publishing_games)
  29. [ **Tools and testing** ](/en-US/docs/Learn/Tools_and_testing)
  30. Client-side web development tools 
    1. [ Understanding client-side web development tools ](/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools)
    2. [ Client-side tooling overview ](/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Overview)
    3. [ Command line crash course ](/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Command_line)
    4. [ Package management basics ](/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Package_management)
    5. [ Introducing a complete toolchain ](/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Introducing_complete_toolchain)
    6. [ Deploying our app ](/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Deployment)
  31. Introduction to client-side frameworks 
    1. [ Introduction to client-side frameworks ](/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Introduction)
    2. [ Framework main features ](/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Main_features)
  32. React 
    1. [ Getting started with React ](/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_getting_started)
    2. [ Beginning our React todo list ](/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_todo_list_beginning)
    3. [ Componentizing our React app ](/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_components)
    4. [ React interactivity: Events and state ](/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_interactivity_events_state)