What are the key characteristics of a Shakespearean sonnet?

In terms of structure, a Shakespearean sonnet has 14 lines and is written in iambic pentameter. This means that has 3 quatrains (4 line sections) and one heroic couplet. The rhyme scheme, therefore, is abab (quatrain 1), cdcd (quatrain 2), efef (quatrain 3), and gg (heroic couplet). according to

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