Eventually you'll reach a point where you need to run
multiple instances of an application or a service for high availability
or to manage increased load. That's what load balancer are for.
There's generally two different types:
There's generally two different types:
Server-side Load Balancing :
What
many people would call a "load balancer" is actually a server-side load
balancer. It can be implemented in hardware or software. The traffic is
sent to a dedicated service that decides where to send the traffic,
using an algorithm like round-robin, to one of the many instances. 
Client-side Load Balancing :
Instead of relying on another service to
distribute the load, the client itself, is responsible for deciding
where to send the traffic also using an algorithm like round-robin. It
can either discover the instances, via service discovery, or can be
configured with a predefined list. Netflix Ribbon is an example of a client-side load balancer.
