nginx load balancing approaches:
round-robin (default)
server with least # of active connections
ip-hashing: based on a hashon ip of the client go to particular node. subsequent requests from the same user will always go to same server. Use for sticky sessions

nginx can be webserver itself (listen to port 80) when you install it on ubuntu

As an example
use vagrant that installs three servers to test on. 
we assign two of them as web01, web02 for webserver and one lb01 as loadbalancer
On webservers
sudo apt­get install ­y nginx 
uname ­n | sudo tee /usr/share/nginx/html/index.html    # replace default nginx page with just name of that machine (web01, web02)