This document discusses signal words used in compare and contrast essays. It identifies two main categories of signal words: comparison signals and contrast signals. Comparison signals indicate similarities between things and include words like "likewise" and "also." Contrast signals indicate differences and include concession words like "although" or "even though" which show similarities and opposition words like "whereas" or "instead" which show direct opposites. The document provides examples of how to use each type of signal word and notes the grammatical structures that should accompany them.