Blue/green deployment – when deploying a new version of your application prepare and run all environment including your app without external access. You can then test it and if everything works fine – switch access to the new environment (disable the old version).

Canary deployment – release the new version of your app to a limited (1 – 10%) part of your clients. That way when anything goes wrong – only a subset of your clients will be affected and you can roll-back the change quickly. Expand number of clients if everything goes fine.