A tie is a curved horizontal line used in standard music notation that extends between the heads of two successive notes of the same pitch and indicates that they are to be played as a single note with a duration equal to the sum of their individual note values. Ties are usually used to connect notes in adjacent measures and indicate that they should be played as a single note. However, they are also used to create note durations that cannot be indicated in any other way, such as a combination of a half note and a sixteenth note. Slurs are similar in appearance to ties, except that they can extend between any number of notes, including notes of different pitches, and indicate that they should be played legato.