An ode is a form of lyric, meaning that it is an expression of thought or feeling. It is often quite complex and addresses something or someone. It praises, celebrates or commemorates its addressee. An ode is generally serious and ceremonious. It is usually elevated in style and because of this it is open to burlesque and poets often parody it quite a lot. There are ‘greater’ and ‘lesser’ odes, this is distinguished by how serious the subject matter is and how elevated the style is. Among ‘lesser odes’ are Anacreontic (which deals with love and drinking) and Sapphic (has a very specific structure).
The Horatian ode
This ode has a regular structure and is named after the Roman poet, Horace. It is homostrophic (it is always in stanzas of the same shape). Its stanzas can be in any metre or of any length. Within the stanzas line length and metre may vary.
The Pindaric ode
This ode is to be sung and danced by performers. It is a tripartite (it has three sections – the strophe, antistrophe (both have the same stanza structure) and the epode). The structure of every section is irregular and their metre and line length may vary.
The Irregular ode
This is confusingly also called the Pindaric ode! It has any number of stanzas. No two stanzas need to have the same shape, metre, line length and rhyme (which can vary from line to line). This ode remains the dominant kind of ode.
I hope this short summary has helped to explain odes! If you have any questions please feel free to comment below and I will answer them for you!