Structure of metal songs

Song contains from introduction (it takes approximately 1 minute), it are only guitars or non guitar introduction, when are usually used instruments like synthesizer or violin or seldom orchestra. Very often are used guitars however. It is often sung according plan: 1. strophe, chorus, 2. strophe, chorus, 3. strophe and in the end chorus, but this doesn’t have to be custom. Often the third strophe is shorter or it isn’t at all. Between 3. strophe and last chorus is often unique instrumental part (heavy metal has there main solo). This part can substitute 3. strophe. Instrumental part contains of instruments, which were in this subsection mentioned.
Ballads (songs mostly without guitar background) are mostly played without percussion with accompaniment piano and often synths (symphonic background).