Can you help me understand a SONNET?

I'M SO CONFUSED!!!!!!!!!!!!!!!!!!!!! Here's the details: SONNET A poem of fourteen lines, iambic pentameter, following one or another of several set rhyme-schemes. The two characteristic sonnet types are: Italian (Petrarchan) The first, the Italian form, is distinguished by its division into the octave and the sestet: the octave consisting of a first division of eight lines rhyming abbaabba and the sestet, or second division, consisting of six lines rhyming cdecde, cdccdc, or cdedce the English (Shakespearean) Instead of the octave and sestet divisions, this sonnet has four divisions: three quatrains (each with a rhyme-scheme of its own) and a rhymed couplet. Thus the typical rhyme-scheme for the English sonnet is abab cdcd efef gg. The couplet at the end is usually a commentary on the foregoing, a closure. Another variation : abab bcbc cdcd ee. what do they mean by abab cdcd and all that stuff? They gave an example, from Romeo and Juliet: Romeo: If I profane with my unworthiest hand quatraina This holy shrine, the gentle sin is this;b My lips, two blushing pilgrims, ready standa To smooth that rough touch with a tender kissb Juliet: Good pilgrim, you do wrong your hand too much, quatrain c Which mannerly devotion shows in this; d For saints have hands that pilgrims’ hands do touch,c And palm to palm is holy palmers’ kissd Romeo: Have not saints lips, and holy palmers too? quatraine Juliet: Ay, pilgrim, lips that they must use in prayer.f Romeo: O, then, dear saint, let lips do what hands do!e They pray: grant thou, lest faith turn to despair.f Juliet: Saints do not move, though grant for prayer’s sake.coupletg Romeo: Then move not while my prayer’s effect I take.g