If you want the processor to ignore and if you want to put character data in your document, then we use XML Comment tag.
Syntax XML Comments
<!-- This is a comments -->
Rules that needs to be remembered for writing the comments
1. You should never have "-" or "--" within the text of your comment, as it might be confusing the XML processor.
2. Never place a comment within a tag.
3. Never place a comment before the XML Declaration