Robots.txt: Discovering unexpected features of the file after 30 years of its existence

In a recent LinkedIn post, Gary Illies, an analyst at Google, highlighted lesser-known aspects of the 30-year-old robots.txt file. This file, which is the foundation of web indexing and web parsing, has remained an important element of SEO practice since its inception. And that's why it remains relevant.

"robots.txt is virtually error-free," Illies said.

He explained that robots.txt parsers are designed to ignore most errors without compromising functionality. This means that the file continues to work even if you accidentally include irrelevant content or make mistakes in directives.

• 📌 Basic directives such as user-agent, allow and disallow are usually recognized and processed, while unrecognized content is ignored.
• 📌 Illies points out the presence of inline comments in robots.txt files, which is quite surprising given their tolerance for errors.
• 📌 The SEO community responded to Illies' post, providing additional context on the practical implications of robots.txt error tolerance and the use of inline comments.

🚀 It's important to understand the nuances of the robots.txt file, as it can help you better optimize your sites. However, despite the useful fault tolerance of this file, it can cause some problems to be missed if not properly managed.

"When working with websites, you can think of an inline comment as a note from the developer about what they want that 'disallow' directive in the file to do," noted Optimisey founder Andrew S.