OBS is a screen recording / streaming software, a tad tricky to get into for casual users. I’ve been using it for several years and various projects, and I absolutely love it. It’s open source and freely available for Windows, macOS and Linux from obsproject.com.
I’ve recorded these videos for friends and viewers who were a little lost, it’s ideal to get started. If you want to delve deeper, I have a full course on OBS called Streaming 101.