​Robots.txt is a text file which contains few lines of simple code.

It is saved on the website or blog's server which instruct the web crawlers on how to index and crawl your blog in the search results.

That means you can restrict any web page on your blog from web crawlers so that it can't get indexed in search engines like your blog labels page, your demo page or any other pages that are not as important to get indexed.

Always remember that search crawlers scan the robots.txt file before crawling any web page.

Each blog hosted on blogger has its default robots.txt file which is something look like this:

User-agent: Mediapartners-Google

Disallow:

User-agent: *

Disallow: /search

Allow: /

Sitemap: http://example.blogspot.com/feeds/posts/default?orderby=UPDATED