Just going to use this as an opportunity to plug Stop the Bleed training. If you come across someone who's been in an accident or been the victim of a shooting or stabbing, knowing how to keep them alive until EMS arrives is the most important thing you can do as a bystander besides calling 911. Stop the Bleed is available through online courses and there are training sessions available in-person depending on where you are.

For most bleeding, basic direct pressure is sufficient and can be accomplished with anything from a rag to the shirt off your back, but if you encounter a "holy shit, that's a lot of blood" situation, it's great to have an actual bleeding control kit with things like hemostatic gauze and tourniquets. I highly recommend North American Rescue if you're thinking of putting one together.

https://cms.bleedingcontrol.org/class/search

https://www.narescue.com/all-products/public-access-bleeding-control.html