Rock bands often have two guitarists, designated "lead" and "rhythm", with the lead player performing the solos and instrumental melody lines while the rhythm player accompanies with chords or riffs. In some cases, two guitarists share the lead role. Most rock music is based around songs in traditional forms. The main formal features are verses, choruses, and bridges. The guitar solo is usually the most significant instrumental section of a mainstream rock song. In other rock-related genres, such as pop and dance music, the synthesizer usually plays this role.