Everybody knows ing but ing is not a grapheme it is a spelling rule. We often add it to the end of verbs and many of you would have heard of “e goes away when ing comes to stay.” The actual rule is e goes away when ing comes to stay or any other suffix that starts with a vowel but more about that latter.

So back to ng, n and g make ng in ring. We also find it with other vowels like in song, bang and lung.  This is why we need to ng without the I turning it into ing.