Blogs, sitemaps and the use of robots.txt is very important when it comes to your website and Google (and many search engines. Why a sitemap is important is because it lets Google easily understand all the pages on your website and what those pages are about. It’s kind of like the card system in libraries that shows you all the books in the library instead of you going through every book on every shelf to find what you are looking for. Robots.txt tells Google’s spiders what pages of your website are o.k. to index into their search engine, if you don’t have it setup correctly your pages might be able to be indexed.
Having a blog is really important for a few reasons. When you create a blog post, it time stamps it and lets Google know you are staying active with your website and not just letting it sit idle. Another reason why having a blog is important is because every blog post you have adds an additional page to your website so if your main site has 5 pages, and your blog has 100 blog posts, in Google’s eyes your site will have a 105 pages (which quite possibly can help you over a competitor that may only have a 5 page website with no blog). The last reason I will mention is if your blog posts have good information that is helpful, not only will they show in Google searches and people can find your blog and in turn find your main website, they may also share it on Social Media like Twitter, Facebook, Google+ and so on.