Word formation is the process of creating new words in a language. This can occur through various methods, such as derivation, where prefixes or suffixes are added to existing words, like adding “-ness” to “happy” to form “happiness.” Another method is compounding, which combines two or more words, such as “tooth” and “brush” to create “toothbrush.” Additionally, conversion allows a word to change its grammatical category without altering its form, like using the noun “run” as a verb. Other techniques include blending, where parts of two words are merged, as in “brunch” from “breakfast” and “lunch.” These processes enrich a language and expand its vocabulary.