How do I recognise a sonnet?

A sonnet is a poem which consists of 14 lines, and is typically written in iambic pentameter with a consistent rhyme scheme of A/B/A/B // C/D/C/D // E/F/E/F // G/G split into 3 quatrains (four lines per stanza) and ending in a rhyming couplet in a Shakspearean sonnet; in a Petrarchan sonnet, however, the poem is spilt into a octave and a sestet (eight and six lines per stanza) with a rhyme scheme of A/B/B/A/A/B/B/A // C/S/E/C/D/E (or C/D/C/D/C/D).