

In online stores Visa and MC are the big ones. If we exclude China, Visa and MC make up 90% of all online purchases worldwide. For online stores they are the two players who matter. Losing one is a significant loss of revenue, losing both will kill the store.
Shamelessly plugging https://linuxupskillchallenge.org/ because if you’re going to set up an Ubuntu home server you might a well know how to use it.