Optimizing for Multilingual and Multiregional SEO

Create a detailed guide on optimizing a website for multilingual and multiregional SEO. Include techniques for: 

1. Identifying target languages and regions.
2. Conducting keyword research for different languages.
3. Structuring URLs and domains for international SEO.
4. Writing and translating content to maintain quality and relevance.
5. Setting up hreflang tags correctly.
6. Leveraging local backlinks and directories.
7. Addressing cultural differences in content and design.

Ensure your explanations are clear and actionable, aimed at helping businesses effectively reach a global audience and improve their search rankings in diverse markets.