Nearly every site has one, they tell search engine spiders and other web robots where they should and shouldn't visit on the site. They can be extremely complex, with different rules depending upon the robot and the area of the site or they can be as simple as two lines long. Learn more about how web robots use the robots.txt file and how to create one that does what you want it to.

Yep, “re-fitted” such files this last week on a variety of sites. More interestingly, I will be keen to see the impact on Google et al as the pages get re-indexed and how the rankings and analytics get affected by implementing robots.txt file.
(I must get out more..)
You are totally right. There are lots of websites that don’t have a Robots.txt. You van tell the bots that they are allowed to index some maps and are allowed to index pages and images. It’s very important to tell the bots that images can be indexed! Thx for your post and sharing your information.
I don’t understand the “linkage” reason. What does that mean? Can you give an example, please?
“linkage” reason. What are you talking about? Where did you read that?
Can anyone guide me to understand the “linkage”.I am not able to get an idea.