An ode is a lyric poem designated to praise a subject. The phrasing and content tends to be formal and serious. Odes were originally sung, most notably in Ancient Greece, but have since become familiar forms in subsequent historical periods such as the Romantic era. One example from Ancient Greece is "Ode to Aphrodite" by Sappho. In this ode, the speaker addresses her subject (Aphrodite) directly but in deference; like a prayer.
In Shelley's "Ode to the West Wind," the speaker addresses the West Wind and describes an analogy between the regenerative power of the wind (and nature) and the impact of Shelley's own poetry.
In both examples, the form of the ode is divided into stanzas, a relatively formal and succinct rhythm and meter. However, odes are not limited to such formal limits. In "Ode to My Socks," by Pablo Neruda, the form is free verse and the subject is a pair of socks; a much more ordinary subject than the classical subjects of an ode such as a god or the power of nature.
In Neruda's ode, he celebrates this ordinary thing to celebrate ordinary life and the thoughtfulness of the gift, but also to praise the usefulness of his socks:
The moral of my ode is this:
beauty is twice beauty
and what is good is doubly good
when it is a matter of two socks
made of wool in winter.
Although the form, rhythm, and meter comes in different packages, the common theme of an ode is the praise of some subject. And this can be anything from socks to a god.