Hackthebox has online machines to hack, it's the best place to learn by practicing. If you are new I would recommend you learning by doing retired machines following Ippsec videos.
HackTheBox academy is the new platform to learn hacking in a more guided way, also a great resource if you want to practice hacking some specific technology!
Tryhackme is a platform with virtual machines that need to be solved through walkthroughs, which is very good for beginners and normal CTFs where you self must hack into the machines.
Rootme is another page for online hosted virtual machines to hack.
Vulnhub has machines to download and then to hack
This site seems to be a community platform
free site with videos and CTFs
This site has a lot of binaries for forensic learning.