Alternative is an adjective meaning available as another possibility or choice.
It can also be used as a noun referring to one of two or more available possibilities.
In music, alternative refers to a genre of rock music that emerged from the independent music underground of the 1980s.
Other common usages include:
1. Alternative medicine - treatments used instead of conventional medical treatments
2. Alternative energy - energy sources that are renewable and environmentally friendly
3. Alternative lifestyle - a way of living that is different from the conventional norms