Load Balancing is pretty much server and network system stress relief.
Computer server systems and networks route hundreds of thousands of millions of data packets each and every second all over the world. Such large amounts of data need to be handled efficiently.
Load balancing spreads the load of data across devices.
If a network has 3 routers and one of them is doing most of the work and the other two are doing very little then this isn’t a very effective way of handling data. The data needs to be managed by all three devices to make it more efficient.
If a web site is getting many tousands of visitors daily it makes sense to spread the load of this usage across multiple servers so that one server isn’t working overtime and so that the site doesn’t grind to a halt.
Load balancing is simply a means of making networks, servers and network appliances operate more effectively.