The tenor voice is the highest of all the main male vocal types.
The name is used to describe the range the singer can meet, with tenors typically being able to sing between C3 and C5 (from one octave below middle C to one octave above it).
The tenor voice was made famous thanks to the 3 Tenors - Luciano Pavarotti, Jose Carreras and Placido Domingo.
The tenor voice is a term that really only explains the vocal range, without paying much attention to other qualities that the singer may have.
To help distinguish further, there are a number of different types of tenor voice in the classical world: 1) Lirico-Leggero Tr: This is the male equivalent of the female's "lyric coloratura", which is the highest of all tenor voices and can handle more technically difficult passages thanks to its lyrical and agile qualities.
2) Lyric: This is more powerful than the above voice, and has the ability to be heard over the orchestra, but without being too heavy.
Pavarotti would be counted as a lyric tenor.
3) Spinto: This shares many qualities with the lyric tenor but is heavier, meaning that the voice can be pushed harder if needed, and won't strain as much.
4) Dramatic: This type of tenor voice typically describes the "hero" of the opera.
5) Heldentenor: This is the German equivalent of the dramatic tenor, though slightly more baritone in its sound.
6) Tenor Buffo/ Spieltenor: This type of tenor is often found playing comic support roles, and the sound of the voice is often manipulated to show a particular characteristic of the character being played at the time.
Tenors often fill the best parts in opera and have the power to bring out a range of emotions in the audience.
But, as you can see, the tenor voice holds within its definition a wealth of possibility, and many tenors are extremely flexible in their roles.