Good question Dear. Disavow links tool specially designed to remove bad and low quality links to your site. You can submit spammy links or unnatural which connected to your site and those submitted links can not count by google algorithm. It increase your reputation due to those bad links or spammy links.
You can go to Googles Central Webmaster blog for assistance you may find the whole use and benefits of this tool.
Disavow link is the new phenomenon in the SEO world through which Matt has conveyed a message to all those who have received the warning message from the Google and they can submit their unnatural links or spam links to it so that they cannot be considered by the crawler and one can start improving their backlinks in a easy way.
A disavow links tool is a tool that allows publishers and webmasters to stop third party sites from negatively affecting a website. This is most often done by competitors pointing unwanted, spammy links toward a website that they see as a threat. This makes the website look like low quality in the eyes of Google, so the site will move down in the rankings. The disavow links tool is now going to be added as a way to stop this type of negative SEO, and the best part is that it puts the webmaster in control.
google search engine is so nice for us to use links to promote our website to be known by our clients .
It's a fantastic Move from Google, Finally a tool that will allow webmasters to control their backlinks profile. We have been hearing a lot from webmasters about the possible negative SEO and its effect in reducing the ranking of a website in Google, and this move will help webmaster counter that. #Much Appreciated Move
To further complicate matters, the file size is limited to 2MB, so if you have a lot of spammy links, you won't get them all on.
I heard that Google releases new disavow links tool to remove the spammy links automatically once you url is submitted.