A digraph is a combination of two letters that together represent a single sound or phoneme in a language. Common examples include "ch" in chair, "sh" in shoe, and "th" in this. Digraphs can be found in various languages and are essential for understanding pronunciation and spelling. In addition to consonant digraphs, there are also vowel digraphs, where two vowels combine to create a single sound, such as "ai" in rain and "ea" in bread. Recognizing digraphs helps improve reading and writing skills, making them an important aspect of language learning.