An infix is a type of affix that is inserted within a word, rather than at the beginning or end. Infixes are less common in English but are found in some other languages, such as Tagalog. For example, in Tagalog, the infix "-um-" can be added to the root word "bili" (to buy) to form "bumili" (to buy). Infixes serve various grammatical functions, such as indicating tense or aspect. They can change the meaning of a word or create a new word altogether. Understanding infixes can enhance one's knowledge of language structure and the diversity of linguistic forms across different cultures.