Common Forms Music theory, explained with Oreos Theory ThingsWilliam Wieland
Popular Music
Pop Song Form Vocabulary
12-bar BluesI - I - I - I,  IV - IV - I - I,  V - IV - I - I
Song Forma a b a(B is the bridge.)
Strophic FormEvery verse uses the same music (Verse = Strophe = Stanza)
Verse / RefrainVerse 1 • Refrain • Verse 2 • Refrain • (etc.)
Classical Music

 Musical Forms (fruit)
Binary FormA B
Ternary FormA B A'(Binary, Ternary & Rounded Binary Compared)
Rounded Binary FormA B Part of A
Sonata FormExposition Development Recapitulation
Rondo FormA B A C AAmerican Sign Language Alphabet
Theme and VariationsA  A' A''...
Bar FormA A B
Multi-movement Sonata (Not only sonatas, but other works like string quartets and symphonies often follow this model.)
1st movementAllegroTonicSonata Form (but other forms are possible including Theme & Variations)
2nd movementSlowNot TonicMany forms are possible including Binary, Ternary, Rounded Binary and Sonata
3rd movementDanceNot TonicCompound Ternary (usually Minuet & Trio or Scherzo & Trio)
4th movementFastTonicRondo Form (Sonata-Rondo or Sonata Form are also possible)