Why is it called BSON?

So BSON is JSON serialized right?

{"hello": "world"} → "\x16\x00\x00\x00\x02hello\x00 \x06\x00\x00\x00world\x00\x00"

But why is it called Binary Json? What does binary stands for?

I always tend to associate binary with 10101010101. But the BSON serialization format above wasn't in 101010101010 form.

Could someone explain for me what the Binary here means so I understand why it's called Binary JSON?