I didn't "skip over" anything. If it's irrelevant to you that something is a submanifold or group, you also don't need to look up the definition. Reading mathe

I didn't "skip over" anything. If it's irrelevant to you that something is a submanifold or group, you also don't need to look up the definition. Reading mathematical definitions on their own just doesn't give you a whole lot of context about the objects they're describing.