What do curved lines in music notation primarily indicate?

Curved lines in music notation, known as slurs, are primarily used to connect notes for smooth playing. This means that when you see these curved lines, it directs the performer to play the notes smoothly and legato without rearticulating each note. This technique allows for a flowing musical line, which is essential for achieving a lyrical and expressive performance.

In contrast, while emphasizing lyrics is important in vocal music performance, it is not the primary function of curved lines in notation. Curved lines do not denote pauses either; pauses are indicated using different symbols, such as fermatas or rests. Additionally, a crescendo, which indicates a gradual increase in volume, is not represented by curved lines but rather by specific symbols that signal the performer to build intensity. Thus, the use of curved lines to indicate a connection between notes is fundamental for achieving a seamless and smooth musical interpretation.