Anycast

It's an load balancing setup in which an application is hosted behind different routing domains but with same IP address. This means, the BGP routers will see which of the routing domains is the nearest and route the packet to that destination.

It's important to that it's not based on the geographical proximity. It depends on AS path length (Number of BGP Routers that must be hopped) or many other router configurations.

Using Anycast for DNS

Cloudfare hosts 1.1.1.1 deploys this IP address on multiple data centers. But the DNS queries goes to the nearest one based on the nearest path selected by the router.

Similar to GeoDNS

This concept is similar to GeoDNS where the DNS returns different IP addresses based on the source IP. Both systems try to achieve the same.