What does a double bar line signify in a piece of music?

In music notation, a double bar line signifies the end of a piece. This is important as it marks the conclusion of the musical work and indicates to performers that they have reached the final note of the composition. It differentiates the ending from other divisions within the piece, such as sections or movements that may be indicated by a single bar line or other symbols.

Other choices relate to different meanings in musical notation. For instance, a single bar line is commonly used to separate measures, and a repeat sign would indicate that a section should be played again, which is visually distinct from a double bar line. Lastly, a change in tempo is indicated by various markings in the music rather than a specific line type. Understanding these notational symbols is essential for interpreting and performing music accurately.