How to use rsync to sync remote and local filesystems or servers

Trying to transfer a website with a lot of files from an old hacked server to a new one I used the following command. I also tried to use the sftp protocol. I also tried to transfer the compressed file to a public folder and download it from there but Apache didn't seem to handle it properly. rsync was and will be the command of my choice for the next years to come it seems. PS: Make sure you also check the related article on DigitalOcean.