'Astrophil and Stella' is a sonnet sequence written by Sir Philip Sidney, first published in 1591, that explores the themes of love, desire, and unattainable beauty through the character of Astrophil, who is in love with Stella. This work is significant in the context of sonnet forms as it combines elements of both Petrarchan and Shakespearean styles while contributing to the evolution of English poetry in expressing emotional depth and complexity.