What does a slur indicate in music notation?

A slur in music notation serves the specific purpose of instructing the performer to connect two or more notes smoothly. This connection typically indicates that the notes should be played in a legato style, where each note is linked seamlessly to the next without any perceptible breaks or articulations between them. This technique helps create a flowing sound, which is essential in various styles of music, especially in choral and orchestral works where the expressiveness of phrasing is important.

By contrast, the other options describe different musical techniques. Playing notes louder involves dynamics, which is denoted by markings such as "f" for forte. Playing notes more quickly could relate to tempo or articulations such as staccato and is not indicated by a slur. Staccato, on the other hand, is a directive for short, detached notes, which is the opposite of what a slur conveys. Understanding the role of a slur helps musicians interpret music accurately and execute the desired phrasing and expressiveness in their performance.