The AWS Application Load Balancer (ALB) is the 2nd member of the Elastic Load Balancing (ELB) family, following the original Classic Load Balancer (CLB) (and since joined by the Network Load Balancer). The ALB provides fully managed, highly scalable, layer 7 load balancing with the ability to perform both path and host-based routing.
The AWS Web Application Firewall (WAF) is a (relatively) recent addition to AWS’s already mature lineup of scalable, fault-tolerant, managed services. The WAF provides AWS customers with a flexible and cost-effective platform that protects web applications from malicious users, content abusers, and DDoS attackers.
The AWS Network Load Balancer (NLB) is the 3rd member of the Elastic Load Balancing (ELB) family, following the original Classic Load Balancer (CLB) and the Application Load Balancer (ALB). The NLB provides highly scalable layer 4 load balancing and introduced the ability to use Elastic IPs (EIP) with ELBs.