Glossary: reverse single crochet
rsc = reverse single crochet
'rsc' means 'reverse single crochet'.
Reverse single crochet is worked exactly like regular single crochet except going left to right instead of right to left. At the end of an sc row, if the next row is reverse sc, you do not turn, but twist your wrist and insert the crochet hook back into the stitch just finished, work a sc, and continue in this way back across.