Which concept is essential for understanding the building blocks of words in a language?

Morphology is the study of the structure of words and the ways in which they are formed. It deals with the smallest units of meaning, known as morphemes, which can be roots, prefixes, or suffixes. Understanding morphology is essential for recognizing how words are constructed and how their meanings can change depending on their morphological components. For instance, knowing that "un-" is a prefix that negates the meaning of a word and that "-ed" indicates past tense allows readers and writers to decode new words and expand their vocabulary effectively.

In contrast, the other concepts, while related to language, do not specifically focus on the building blocks of words. Syntax pertains to the arrangement of words in sentences, the lexicon refers to the vocabulary of a language, and grammar encompasses a broader set of rules that govern how language is used, including syntax and morphology. Thus, while all these elements contribute to language comprehension and usage, morphology is the most critical for understanding how words are formed and meaning is conveyed through their structure.