Website changing servers/IPs

Can anyone explain to me how a website can change between different web servers?

Is this load balancing? or DNS management?

Can anyone please explain this technology.

To experience this please try and you will see that their server changes to different server locations with different IP often. You will need to refresh and refresh to see if the server changes.

I suppose that is

Is this load balancing?

But can you please explain nature of asking. Would you like to have the same done with your web sites? That is not cheap at all and I suppose you need to think twice before you get that.
Please explain what exactly do you want to reach.

That can be by load balancer. This normally switches between servers in same DC. It can also be based on DNS.

One site showing as multiple locations is indeed a form of load balancing.

This could be done in one of many different ways - the easiest is multiple servers with different ip’s, all added to the dns.

A further way would be to have a load balancing box sat in front of multiple web servers.

Again, depends on the setup.