Legato is a term indicating that a passage, movement, or entire composition is to be played or sung smoothly, i.e., without intervening silences. The Italian legato means "linked together" or "bound". In musical notation, the notes to be played are joined by curving lines. This not imply, as is often supposed, a lack of articulation, accent, or coloration.
The first note of a group of slurred notes is played with a very slight emphasis.
In the context of guitar music, legato is achieved by techniques that avoid the need to pluck the strings, such as slurs (hammer-ons and pull-offs) and slides. With regard to classical stringed instruments, legato refers to playing notes with a full bow. In order to achieve the effect, the violinist needs to play with controlled wrist movements of the bowing hand and often in conjunction with vibrato.
The opposite of legato is staccato.