O the ode! How we do love thee!
An ode is a type of lyric poetry that sings the praises of the poem's subject. In ancient times, the ode was usually performed at a ceremonial occasion, with music. More recently, one of the most glorious symphonic movements of all time, Beethoven's "Ode to Joy" from his Ninth Symphony, is a musical setting of an ode. It's a serious and ceremonial form, the kind that might have been sung after a big banquet. Most modern odes still have a very formal, traditional sound. Many of them are poems of praise, or general appreciation.
Nowadays, we often use the phrase "ode to" as an indication of formal praise. As in, "His speech was an ode to his favorite sports team." The Romantics made a big deal out of writing odes and John Keats was the master. He wrote odes to all kinds of things—nightingales, Grecian urns, even melancholy.
Some odes follow the formal rules set by the two most famous Greek writers of odes, Horace and Pindar. These poems are called—surprise, surprise—Horatian and Pindaric, respectively. But other odes, like Keats's, follow a form and meter all their own.
So next time you're feeling swoony, read some Keats and write an ode all your own—to your main squeeze, to sunshine, or even to cheese. Anything goes.