AWS ELB is a network load balancer service provided by Amazon Web Services for distributing traffic across multiple targets, such as Amazon EC2 instances, containers, IP addresses, and Lambda functions.
Apache is a free and open-source cross-platform web server software.
Mod_jk is an Apache module used to connect the Tomcat servlet container with web servers such as Apache, iPlanet, Sun ONE (formerly Netscape) and even IIS using the Apache JServ Protocol. A web server waits for client HTTP requests.