Robots.txt file is a text file. We can create this file in Word Note. With this file we can point to any bot. The bot will crawl any page of our website and will not crawl any page.This is robots.txt file.

When any bot comes to crawl our website, it first comes to the file of the website. If robots.txt file is on the website, the bot will crawl the website following the instructions in the file. If this file is not on the website then the bot will crawl all the files.Hear bot means any search engine crawler.
So in a word we can understand robots.txt file is an instruction through which we can lock or unlock the page or post of our website from all bots or users. This means that I indirectly tell whether a bot or user will come to any page or post.
Why use robots.txt file
When the boat comes to crawl the website, then has a specific time for how long he will crawl. Not that he will continue to crawl for long. Time is fixed in his work. The time it takes to crawl a bot is called crawling budget. This crawling will end bot crawl within budget.
The website contains some files or pages that are not important. So we don’t want to waste our crawling budget by crawling those pages or post bots. This can be detrimental to us because the bot has limited time to crawl my important files and can’t crawl important posts or pages. Because he have crawling budget. So we make it easier for the bot to use the robots.txt file to crawl and index important posts or pages.
Eventually, it became known that robots.txt files play a role in indexing our website in any search engine. This makes it easier for bots to crawl important pages or posts on our website.