Rss is a family of Web feed formats used to publish frequently updated works – such as
in a standardized format.
You don't have to take a subscription or to give your email to receive update information.
The feed is generally and URL like for instance (Rss Feed from Wikipedia)
http://en.wikipedia.org/w/index.php?title=Special:RecentChanges&feed=rss
You can found this URL in the page of the website of in the head of your browser via the RSS icon.
Example: (S'abonner a … in French for Subscribe to)
For Chrome - you need to add en extension RSS Subscription Extension (by Google)
You must use a Rss Reader software to be able to read the last update.
To subscribe, you need to get the URL feed and gives it to your reader.
This is generally done via Browser extension. See url
See https://validator.w3.org/feed/