Cloudflare is a service (or a CDN, Content Delivery Network) that deals with the security and performance features (among other things) of a wide network of websites. It acts as a reverse proxy, a middleman between you—the user—and a given website. When you go visit that site, you’ll be directed to one of the Cloudflare’s servers instead of the actual site’s servers.
This allows Cloudflare to ensure you’re a legitimate user (thus protecting against denial of service attacks), load the site faster (since they’ve cached certain parts of the site), and protect against downtime (since they have multiple servers worldwide and can fall back on any server if one has a problem).
Cloudflare safeguards DDoS attackers don’t get their traffic through to the actual website.
In short
Cloudflare aims to make sites faster and more secure, and it’s a service a lot of websites use.
Cloudflare protects and accelerates any website online. Once your website is a part of the Cloudflare community, its web traffic is routed through its intelligent global network. It automatically optimizes the delivery of your web pages so your visitors get the fastest page load times and best performance. Also, its big benefit is also to cater to the user problem of migration. It means that when you run your website through it, you don’t worry about the changes and migration of your website from one hosting vendor to another. You just change the DNS settings in the CloudFlare and there is no overhead to change the whole directories.