While this is certainly okay, it is still most commonly called a double bar line or double bar. I have seen in many books where a double bar line can also be referred to as a final bar line. Just like bar lines, they will always pass through the entire staff vertically, including the grand staff. If not, then it is something else we’ll talk about more in just a moment. Every time you see this marking, the thick line will always be on the outside.
The inner line is thin while the outer line is very thick. That is where the “double” comes from in the name of the symbol. The double bar line is made up of two lines total. It’s like one giant “stop sign” commanding you to come to a screeching halt when you see it. The purpose of this marking is to tell us that it is the end of the music. At the end of every song you read, you will find a double bar line (or double bar).
