GNS3 is a Cisco Simulator that lets networking people run Cisco Router software on their PC. This way you don't need real hardware anymore which saves money/time and it's more convenient!
I'm working as a Cisco Teacher and I am currently working to get my website "GNS3 Vault" online. The goal of the website is to have a collection of tasks/scenarios/workbooks people can download so they can practice working with Cisco Routers by using the GNS3 software.
My goal is to upload my own tasks/scenarios that i created for students but people are also able to upload their own stuff they created by using the GNS3 software.