Short answers, pulled from the story.
Shakespeare's 154 sonnets were first published together in a quarto in 1609. Thomas Thorpe entered the book in the Stationers' Register on the 20th of May 1609, and the quarto was printed by George Eld.
The identity of Mr. W.H., described as "the only begetter" of the sonnets, remains unknown. The most commonly proposed candidates are William Herbert, the Earl of Pembroke, and Henry Wriothesley, the Earl of Southampton, though scholars have also suggested a printer named William Hall, Sir William Harvey, and others.
The Dark Lady is an unnamed woman addressed in Sonnets 127-152, described as having black hair and "dun" skin. Her real-world identity is unknown; Lucy Negro, Mary Fitton, and Emilia Lanier are among those who have been suggested.
Shakespeare wrote 154 sonnets published in the 1609 quarto, plus six additional sonnets embedded in the plays Romeo and Juliet, Henry V, and Love's Labour's Lost, and a partial sonnet in the play Edward III.
The standard Shakespearean sonnet follows the rhyme scheme ABAB CDCD EFEF GG, consisting of three four-line quatrains followed by a final couplet, written in iambic pentameter. The exceptions are Sonnets 99, 126, and 145, which vary this pattern.
The Fair Youth is the unnamed young man addressed in Sonnets 1-126. His identity has never been confirmed; Henry Wriothesley, the 3rd Earl of Southampton, and William Herbert, the Earl of Pembroke, are the most frequently proposed candidates.