A mandolin (Italian: mandolino pronounced [mandoˈliːno]; literally "small mandola") is a musical instrument in the lute family and is usually plucked with a plectrum or "pick". It commonly has four courses of doubled metal strings tuned in unison (8 strings), although five (10 strings) and six (12 strings) course versions also exist. The courses are normally tuned in a succession of perfect fifths. It is the soprano member of a family that includes the mandola, octave mandolin, mandocello and mandobass. 

There are many styles of mandolin, but four are common, the Neapolitan or round-backed mandolin, the carved-top mandolin and the flat-backed mandolin. The round-back has a deep bottom, constructed of strips of wood, glued together into a bowl. The carved-top or arch-top mandolin has a much shallower, arched back, and an arched top—both carved out of wood. The flat-backed mandolin uses thin sheets of wood for the body, braced on the inside for strength in a similar manner to a guitar. Each style of instrument has its own sound quality and is associated with particular forms of music. Neapolitan mandolins feature prominently in European classical music and traditional music. Carved-top instruments are common in American folk music and bluegrass music. Flat-backed instruments are commonly used in Irish, British and Brazilian folk music. Some modern Brazilian instruments feature an extra fifth course tuned a fifth lower than the standard fourth course.
How many strings do the most common mandolins have?
How are they tuned?
Are there other string combinations?
How many strings in those?
Are there specialized styles of mandolins?
How many are common?
What are they?
Are they used specifically for different music?
What is the flat-backed used in?
What are the Neapolitan most used in?
What about the carved-top?
What is the mandolin called in Italian?
What does it mean literally?
8 strings
It commonly has four courses of doubled metal strings tuned in unison (8 strings)
in a succession of perfect fifths
The courses are normally tuned in a succession of perfect fifths.
yes
 It commonly has four courses of doubled metal strings tuned in unison (8 strings), although five (10 strings) and six (12 strings) course versions also exist.
10 strings and 12 strings
 It commonly has four courses of doubled metal strings tuned in unison (8 strings), although five (10 strings) and six (12 strings) course versions also exist. 
yes
There are many styles of mandolin, but four are common, the Neapolitan or round-backed mandolin, the carved-top mandolin and the flat-backed mandolin. The round-back has a deep bottom, constructed of strips of wood, glued together into a bowl. The carved-top or arch-top mandolin has a much shallower, arched back, and an arched top—both carved out of wood. The flat-backed mandolin uses thin sheets of wood for the body, braced on the inside for strength in a similar manner to a guitar. Each style of instrument has its own sound quality and is associated with particular forms of music. Neapolitan mandolins feature prominently in European classical music and traditional music. Carved-top instruments are common in American folk music and bluegrass music. Flat-backed instruments are commonly used in Irish, British and Brazilian folk music. Some modern Brazilian instruments feature an extra fifth course tuned a fifth lower than the standard fourth course.
four
There are many styles of mandolin, but four are common, 
the Neapolitan or round-backed mandolin
There are many styles of mandolin, but four are common, the Neapolitan or round-backed mandolin,
yes
Each style of instrument has its own sound quality 
Irish, British and Brazilian folk music
Carved-top instruments are common in American folk music and bluegrass music. Flat-backed instruments are commonly used in Irish, British and Brazilian folk music. 
European classical music and traditional music
Neapolitan mandolins feature prominently in European classical music and traditional music.
American folk music and bluegrass music
Carved-top instruments are common in American folk music and bluegrass music. 
mandolino
Italian: mandolino pronounced [mandoˈliːno]
small mandola
 literally "small mandola"