The las two lines of Shakespeare sonnets can be described according to this three statements:
-They are referred to as a couplet: two consecutve rhyming lines.
-They rhyme with each other (though this is not always the case).
-They change the sonnet´s rhythmic pattern: a Shakespearean sonnet has 14 lines. The first 12 are divided into 3 quatrains, of 4 lines each were the topic and problem are established. The rhyme scheme is abab cdcd efef. This is solved in the last two lines, where the rhyming scheme is gg.
For example:
When I / do COUNT / the CLOCK / that TELLS / the TIME (Sonnet 12)
When IN / dis GRACE / with FOR / tune AND / men's EYES
I ALL / a LONE / be WEEP / my OUT/ cast STATE (Sonnet 29)
Shall I / com PARE/ thee TO / a SUM / mer's DAY?
Thou ART / more LOVE / ly AND / more TEM / per ATE (Sonnet 18)