Lower case refers to the smaller form of letters in the alphabet, as opposed to upper case, which consists of larger letters. In written language, lower case letters are used for most words, including nouns, verbs, and adjectives, except in specific cases like the beginning of sentences or proper nouns. The use of lower case letters is essential for readability and clarity in text. For example, in the English language, the letter "a" is lower case, while "A" is upper case. Understanding the distinction between these two forms is fundamental in writing and typography, impacting how information is conveyed.