What is the use of Remote Action notation in Salesforce?

The RemoteAction annotation is used in Visualforce page then it is called via JavaScript.

Ex:

global with sharing class AccountRemoter {

public String accountName { get; set; }
public static Account account { get; set; }
public AccountRemoter() { } // empty constructor

@RemoteAction
global static Account getAccount(String accountName) {
account = [SELECT Id, Name, Phone, Type, NumberOfEmployees
FROM Account WHERE Name = :accountName];
return account;
}
}

<script type="text/javascript">
function getRemoteAccount() {
var accountName = document.getElementById('acctSearch').value;

Visualforce.remoting.Manager.invokeAction(
'{!$RemoteAction.AccountRemoter.getAccount}',
accountName,
function(result, event){
if (event.status) {
// Get DOM IDs for HTML and Visualforce elements like this
document.getElementById('remoteAcctId').innerHTML = result.Id
document.getElementById(
"{!$Component.block.blockSection.secondItem.acctNumEmployees}"
).innerHTML = result.NumberOfEmployees;
} else if (event.type === 'exception') {
document.getElementById("responseErrors").innerHTML =
event.message + "<br/>\n<pre>" + event.where + "</pre>";
} else {
document.getElementById("responseErrors").innerHTML = event.message;
}
},
{escape: true}
);
}
</script>

THanks