Okay, I need to create a professional wiki-style document about SEO under the categories of Technology > Web Development > Marketing Tools. Let me start by understanding the requirements.

First, the structure: H1 for the title, an overview section, several sections with H2 and H3 headings, and maybe references or related documents. The content needs to be accurate, objective, detailed enough, easy to read, and use technical terms with explanations. Also, markdown formatting with proper hierarchy, lists, tables, code blocks if needed, and at least 800 characters.

Starting with the title. It should be "SEO" as given. Then an overview section explaining what SEO is, its importance in web development and marketing. Next sections could be on On-Page SEO, Off-Page SEO, Technical SEO, Tools, Best Practices, Challenges, and maybe a conclusion or references.

For each section, I need to elaborate. For example, On-Page SEO would include title tags, meta descriptions, content optimization, etc. Each of these can have H3 headings. Similarly for other sections.

I should make sure to explain technical terms like "meta description" or "backlinks" in simple terms. Maybe use bullet points for lists of tools or best practices. Also, check if any code examples are needed, but since SEO is more about strategies than coding, maybe not necessary unless discussing structured data markup.

Need to ensure the content flows logically, covers all aspects without being too shallow. Check that each section has enough depth. For example, under Technical SEO, discuss site speed, mobile optimization, crawlability, etc.

Also, include some examples or real-world applications where possible. Maybe mention popular tools like Google Analytics, SEMrush, Ahrefs. But avoid promoting specific products unless it's standard knowledge.

Check for accuracy: make sure the information is up-to-date, especially since SEO practices can change with search engine algorithms. For instance, emphasizing user experience and mobile-first indexing as per recent trends.

Avoid any markdown in the thinking process, but when writing the actual document, use H1, H2, H3 properly. Use bold or italics for emphasis if needed, but stick to standard markdown.

Finally, ensure the total length is over 800 characters. Let me count: each section should have enough content. Maybe around 5-6 sections with a few paragraphs each. Also, include a references section with links to official sources like Google's SEO guidelines or Moz.

Wait, the user mentioned "필요시 참고 자료나 관련 문서 섹션" so I need to add that at the end. Maybe list some authoritative resources.

Now, putting it all together step by step, making sure each part is covered and meets the requirements.