We recommend using responsive web design because it:

• Helps Google’s algorithms accurately assign indexing properties to the page rather than needing to signal the existence of corresponding desktop/mobile pages.
• Requires less engineering time to maintain multiple pages for the same content.
• Reduces the possibility of the common mistakes that affect mobile sites.
• Requires no redirection for users to have a device-optimized view, which reduces load time. Also, user agent-based redirection is error-prone and can degrade your site’s user experience.
• Saves resources when Googlebot crawls your site. For responsive web design pages, a single Googlebot user agent only needs to crawl your page once, rather than crawling multiple times with different Googlebot user agents to retrieve all versions of the content.
• This improvement in crawling efficiency can indirectly help Google index more of your site’s content and keep it appropriately fresh.
• Makes it easier for users to share and link to your content with a single URL.