This poem by John Keats, one of the most well-known Romantic poets, is in the form known as an ode, which is a type of poem that is usually intended to celebrate a particular person or thing. The textbook definition is usually a variation of the following: "a lyric poem in the form of an address to a particular subject, often elevated in style or manner and written in varied or irregular meter."
The title of this ode indicates the poem is dedicated to the season of autumn, and Keats writes a very lofty and moving ode to this season. Keats could have created any number of possible titles, but keeping it so simple and yet so wide open (as opposed to naming it after the month in which he was inspired to write it, or after a particular image or idea) allows the reader to meditate upon the entire season of autumn, its warm beginnings, journey through abundance and harvest, and then to its beginning of dormancy in preparation for winter. The imagery suggests humans are deeply tied to this season, as it embodies both fullness and life, as well as decay and death, in the sights and sounds of the cycles of nature. By giving the poem this title, Keats encourages readers to allow themselves to be as moved as he is by the beauty of this season, almost as if it is a love song or an admired person who deserves to be honored.
Keats crafted one of the most well-loved poems on autumn. It is a very sensual poem, with imagery that conjures sounds, tastes, smells, and textures, as well as visuals. The poem is the basis for the titles of the series of very popular "Sandman" graphic novels by Neil Gaiman, the first of which is called "Season of Mists," the first line of Keats's poem. In this way, Gaiman's work is a sort of ode to Keats's poem, which shows the relevance and significance of Keats' work centuries after he lived.