In the context of poetry, 'gg' refers to the rhyme scheme commonly found in sonnet forms, specifically in the closing couplet of a Shakespearean sonnet. This notation indicates that the last two lines of the sonnet rhyme with each other, providing a sense of resolution and finality to the poem's themes. The use of 'gg' enhances the musical quality of the poem and emphasizes key ideas presented throughout the sonnet.