German grammar was revised a number of years ago and some things were changed or modified; the so called ßset was one of them and nowadays the double ss is preferred!
still, strict rules apply - and in this case the "ß" is still in use (as always when following an umlaut ä, ö, ü)
Yeah, modern German is largely abandoning the esset and umlauts. It's good to know them, but I was very surprised that this wouldn't accept ss for the esset. It accepts "ue" and "oe" etc, but not ss? It's too slow otherwise!
Modern German is not abandoning ß, ä, ö, ü. Nobody in Germany would write ae, oe, ue instead of ä, ö, ü, exception is if you don't have the possibility to write ä, ö, ü, e.g. because you use a foreign keyboard layout etc. The use of ß was changed some years ago (made (perhaps) mor logical), but still there's many words where you need ß. It's only written "ss" if you cannot use the "ß" letter, same story as for ä, ö, ü.
as a noun: "Grüße an deine Familie" = "Greetings/Say hi to your family" , as a verb: "Ich grüße den Lehrer" = "I greet/am greeting the teacher"
Kind of silly not allowing ss for esset character. In Switzerland, esset is not used, it is always replaced with ss.
As was said earlier the esset is used in germany after umlauts. Switzerland uses their own sort of german.
For those who do not have the letter ß in their keyboards, I tell you a way I found to write it, not so easy, but... well, it's a combination of 5 keys. You can press ALT+0+2+2+3 (0223), this is called like "close s lowercase latin letter". I did not find an uppercase. anyone know? (whether it has I guess). Besides, I think there exists a combination of 3 numbers, but I don't know.