Letter case

Letter case is the difference between big letters, called uppercase or capitals, and small letters, called lowercase. In many languages, there are two sets of letters: one set is uppercase, and the other is lowercase. For example, the letter C looks almost the same as the letter c, but the letter A looks very different from the letter a. Even though they look different, both versions of a letter have the same name and sound the same.

We usually mix uppercase and lowercase letters when we write to make text easier to read. Capital letters are often used at the beginning of sentences or in special names, like proper nouns. Lowercase letters are more common in everyday writing.

Sometimes, we use only one type of letter. For example, in engineering design drawings, people often use only uppercase letters because they are easier to see when the letters are very small. In mathematics, uppercase and lowercase letters can mean different things. For example, a lowercase x might represent a number, while an uppercase X might represent a whole group of numbers or a set.

Terminology

The words upper case and lower case can be written in two ways: either as two words together, like upper case, or connected with a hyphen, like upper-case. They also can be written as one word, like uppercase or lowercase. These words come from old printing ways. In printing, letters were kept in special shallow boxes called type cases. Big letters, or capital letters, were kept in a box above the box that held the small letters.

Majuscule means any kind of writing where the letters are all about the same height, without parts that go much above or below the main lines. These letters used to be used for whole books, but now they are mostly used as the big, or uppercase, letters we use today.

Minuscule means small, lowercase letters. In old writing, these letters had parts that went above and below the main lines, so they needed more space to write. Over time, these became the small letters we use in writing today.

Typographical considerations

The shapes of lowercase letters can look like smaller versions of their uppercase counterparts, like "C/c" and "S/s", or they can look very different, like "D/d" and "G/g". The way letters look depends on the typeface and font used.

Big letters, or majuscules, are usually all the same height, but small letters, or minuscules, can vary. Some small letters have parts that rise above the normal height, called ascenders, like b, d, f, h, k, l, and t. Others have parts that go below the normal height, called descenders, like g, j, p, q, and y.

Bicameral script

Some writing systems use two different sets of letters: one set is larger (called uppercase or capitals) and the other set is smaller (called lowercase). These writing systems are called bicameral scripts. They include the Latin, Cyrillic, Greek, Coptic, Armenian, Glagolitic, Adlam, Warang Citi, Old Hungarian, Garay, Zaghawa, Osage, Vithkuqi, and Deseret scripts. Languages written with these scripts use letter case to make text clearer. The Georgian alphabet has different forms, but modern Georgian language does not use case differences.

Most other writing systems do not change between uppercase and lowercase letters. These are called unicameral scripts. This includes many syllabic and other non-alphabetic scripts.

In scripts that do use two cases, lowercase letters are usually used for most of the text. Capital letters are used to start sentences, for proper nouns, and for emphasis when bold text is not available. Acronyms are often written in all capital letters, depending on the situation.

Capitalisation

Main article: Capitalisation

Capitalisation means writing a word with its first letter in uppercase and the rest in lowercase. Rules for capitalisation differ by language but often include capitalising the first word of a sentence and all proper nouns.

In English, capital letters are used at the start of sentences, for proper nouns, and for certain words like the days of the week and months. The word "I" is always capitalised. Some words change meaning based on whether the first letter is capitalised.

Different languages have different rules. For example, in German all nouns are capitalised, while in many other languages the days of the week and months are not. Informal writing, like texting or handwritten notes, often does not follow these rules because it is not formal.

Stylistic or specialised usage

In English, different ways of using uppercase and lowercase letters are used for various purposes:

Sentence case
"The quick brown fox jumps over the lazy dog"
This style capitalizes the first word of a sentence and any proper nouns, following the usual rules of English writing.

Substantive capitalization
"The quick brown Fox jumps over the lazy Dog"
This older style, popular in the 1600s and 1700s, capitalizes all nouns to show their importance. It is still used in modern German orthography.

Rhetorical capitalization
"The Quick Brown Fox jumps over the Lazy Dog"
Here, specific words are capitalized to give them extra emphasis or importance, often seen in poetry.

Title case
"The Quick Brown Fox Jumps over the Lazy Dog"
In this style, most words are capitalized except for small words like articles and prepositions. It is commonly used for book and article titles.

Start case
"The Quick Brown Fox Jumps Over The Lazy Dog"
This is like title case but capitalizes every word, often used in computing.

All caps
"THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG"
Using only capital letters can make text look like shouting. It is sometimes used for emphasis or in special designs.

Small caps
"The quick brown fox jumps over the lazy dog"
These are smaller, uppercase-like letters used to make text stand out without using regular capital letters.

All lowercase
"the quick brown fox jumps over the lazy dog"
Writing everything in lowercase can seem casual or artistic. It is often used in text messages and some music titles.

Case folding and case conversion

In computing, each uppercase and lowercase letter is given its own special code. Software can change between these two forms by linking them together. This helps computers treat letters the same, even if they look different. For example, when searching, computers might ignore case so that "Cat" and "cat" are seen as the same.

Different systems treat letter case differently. For example, passwords usually care about case to make them harder to guess. But when searching, case is often ignored so that small differences don’t matter. Special tools in programs like word processors make changing case easy with just a click or a keyboard shortcut. Programming languages also have simple ways to change text between uppercase and lowercase.

History

See also: Initial

At first, alphabets were written only in big letters called majuscules. When people wrote quickly with a pen, the letters became simpler and rounder. This led to the creation of smaller letters called minuscules.

In Latin, old papers from Herculaneum show early small letters like "d", "h", and "r". Both big and small letters existed, but they were used in different styles. Later, a special style called the Carolingian minuscule was created for faster, easier reading.

The way writing developed in Western Europe can be split into four main periods, each with its own styles of big and small letters. Over time, rules about when to use big letters changed. For example, English language stopped making nouns bigger, but German language still does.

Similar changes happened in other writing systems, like the Greek alphabet. The first known Greek text using small letters dates back to 835.

Type cases

In printing, individual letter blocks are kept in shallow wooden or metal drawers called "type cases". These cases have many small sections for different letters.

The words "upper" and "lower" case come from how these cases were stored. The case with big letters was placed higher on the desk, while the case with small letters was lower and easier to reach.

Different patterns of cases exist, with sections for small letters sized based on how often they are used. The person setting the type would take letters from these sections and place them upside down to build lines of text.