The document discusses forming comparative adjectives in English. It provides two main rules:
1. For single-syllable adjectives, add "-er" to the end of the adjective and use "than" to indicate comparison, such as "colder than".
2. For multi-syllable adjectives, use "more" before the adjective and "than" to indicate comparison, such as "more expensive than".
Examples are given to demonstrate how to make short adjectives like "small", "tall" comparative by adding "-er", and how longer adjectives become comparative by adding "more" rather than changing the adjective form.