Continuing our discussion of Sonata Form…
The development usually starts in the secondary key, but quickly moves to tonicize a number of other key areas. These tonicizations are usually brief. If the sonata is a Classical-era work, you can usually identify the start of the development as immediately after the interior repeat sign. Some later works drop the repeated sections altogether. In this case, you need to compare the recap to exposition, and look for significant divergence in the exposition. This would usually indicate the start of the development.
The development sections develops themes and motives, mostly from the exposition. It often ends with a retransition, where V(7) of the original primary key is prolonged, leading to the recapitulation.
A return of the exposition with all themes in the primary key. Often there will be significant changes in the transition, since there is no modulation. There may be other differences as well, including the shortening of theme groups. Note: it is possible for minor-key movements to have the second theme of the recap in the parallel major key. It is also possible (although not typical) that the second theme group may be in some other key than the primary or secondary keys.
Coda or Codetta
The term coda usually implies an additional (and substantial) section of new material after the end of the recapitulation, with no corresponding material in the exposition. A codetta is usually just a few phrases of terminative music in the primary key.
By definition, any music in a coda or codetta must not correspond to anything at the end of the exposition.