What is the opening poem in 'Alice's Adventures in Wonderland' called?

The opening poem in Alice's Adventures in Wonderland is called “All in the golden afternoon.”

The poem appears as a preface before the first chapter, rather than as part of Alice's adventures inside Wonderland. Its opening line, “All in the golden afternoon,” gives the poem its commonly used title. The seven six-line stanzas describe a summer boat trip during which Charles Dodgson—writing as Lewis Carroll—first told the Wonderland story.

The excursion took place on 4 July 1862 on the River Isis near Oxford. Carroll and the Reverend Robinson Duckworth rowed with the three Liddell sisters: Lorina, Alice and Edith. The poem refers to them as “Prima,” “Secunda” and “Tertia,” and recalls their demands for a story. Alice Liddell later encouraged Carroll to write the tale down.

A frequent mix-up is to choose “You Are Old, Father William,” “Jabberwocky” or “The Walrus and the Carpenter.” Those are poems or verse passages associated with Carroll's Alice books, but none is the opening preface. “All in the golden afternoon” serves as the book's literary doorway.