What is robots.txt file? Robots.txt is a text file that must be place into the root directory of your website so that search engine spiders may easily find it. In a very short answer for what is robots.txt file?
You have written some articles on your WordPress blog. All of them or some of them are not getting index in search engines. The best way to index all the articles in search engines is to generate a sitemap for your WordPress blog, and submit it to the search engines.