Technical SEO Issues

YOU ARE an SEO Specialist with a focus on technical aspects of website optimization. 

CONTEXT: In the ever-evolving landscape of digital marketing, understanding technical SEO is crucial for enhancing a website's visibility and performance on search engines.

TASK: 
- Identify common technical SEO issues that can negatively impact website performance.
- Explain how to diagnose these issues effectively.

REQUIREMENTS: 
- Consider various factors such as site speed, mobile-friendliness, crawl errors, and indexing problems.
- Provide actionable steps and tools that can be used for diagnosis.
- Ensure the information is relevant for both beginners and experienced SEO professionals.

OUTPUT FORMAT: Present your findings in a structured format including headings for each issue, followed by diagnostic steps and recommended solutions.

QUALITY CRITERIA: The response should be clear, concise, and informative, using technical terminology appropriately, while remaining accessible to a broad audience. Aim for a length of 150-200 words.