Short answers, pulled from the story.
A lute is any plucked string instrument with a neck and a deep round back enclosing a hollow cavity, usually with a sound hole. The player plucks the strings with one hand while the other frets, or presses, the strings against the fingerboard to change pitch. It may be either fretted or unfretted.
The words lute and oud possibly derive from the Arabic al-ʿoud, which literally means the wood. The name may refer to the wooden plectrum, the thin strips of wood forming the back, or the wooden soundboard that set it apart from skin-faced instruments.
Iconographic evidence pushes the lute back to about 3100 BC, including a cylinder seal in the British Museum showing a woman playing a stick lute. The short-necked line that became the European lute developed east of Mesopotamia, in Bactria and Gandhara, into a short almond-shaped instrument.
The Moors brought their ud to Andalusia when they conquered it in 711, and a second route ran through Sicily via Byzantine or Muslim musicians. By the 14th century lutes had spread across Italy and into German-speaking lands, with lute-making families established at Füssen by 1500.
Lute strings are arranged in courses of two, except the highest course, a single string called the chanterelle. An 8-course Renaissance lute usually has 15 strings, and a 13-course Baroque lute has 24, while some instruments carried up to 35 strings.
Francesco Canova da Milano, who lived from 1497 to 1543, is acknowledged as one of the most famous lute composers in history. England's John Dowland and Germany's Silvius Leopold Weiss were also major figures, and Johann Sebastian Bach transcribed some of Weiss's works for keyboard.
The lute was relegated to continuo accompaniment over the Baroque era, superseded by keyboard instruments, and almost fell out of use after 1800. It was revived through the early music movement of the twentieth century, led by pioneers such as Julian Bream, Walter Gerwig, and Diana Poulton.