Adjectives are words that describe nouns and provide information about their size, age, color, origin, or opinions. They typically come before the noun they describe. Adjectives do not change based on number and can describe physical feelings or emotions using verbs like "be", "feel", "seem", and "look". Adjectives ending in "-ed" describe emotions or feelings, while "-ing" adjectives describe actions or things and function like other adjectives. The difference is that "-ed" describes how one feels and "-ing" describes a thing or action.