D Facts For Kids

D (big D) and d (small d) are the fourth letter of the Latin alphabet. People say its name as "dee." You see this letter in English and many other languages that use the Latin alphabet, which is the same letter set used for signs, books, and most printed words you read every day.

The letter usually stands for the sound /d/, the short, strong sound at the start of words like dog, door, and day. Because it is a simple, common sound, the letter shows up a lot in writing and speech.

Long ago, alphabets grew from picture symbols. One ancestor of D was the Semitic letter Dāleth, which may have started as a drawing of a door or a fish. People who used these signs lived thousands of years ago, so the shape and meaning changed as the signs moved from place to place.

The ancient Greeks borrowed the idea and made the letter into delta (Δ), which looked different but kept the same sound. The Romans then adapted the Greek letters into the Latin alphabet we use now. Other old alphabets, like Etruscan, kept forms of the letter, too.

The small letter d you write by hand is made of a round part plus a tall line on its right. This is the lowercase form. The big letter D is a straight line with a curve on the right. Both forms show up in books and signs.

In English, the letter d usually makes the /d/ sound, the same sound at the start of dog, doll, and dad. It also appears inside and at the end of words, as in ladder or bed. D is one of the letters you see fairly often when reading and writing.

In many languages that use the Latin alphabet, D makes a sound like the English /d/. That is true for most western European languages. But some languages use D for different sounds, or mix it with other letters.

For example, in Vietnamese the letter d can sound like a z or a y depending on the region, so words with the same spelling can sound different. In Fijian, d is pronounced like a quick "nd"—a soft n plus d together, like the sound in candy. These differences show how one letter can do different jobs in different languages.

D does more than stand for a sound. In the counting system called hexadecimal (base 16), the letter D means the number thirteen. In old Rome, the capital D was a number too — it stood for five hundred. When you see a small d before a unit, like decimeter, it can mean “one tenth.”

Letters are also used as short codes. For example, .de is the internet ending for Germany and the letter D appears on German cars to show where they come from. Scholars sometimes use a single D to name old books or manuscripts, and long ago people wrote “d.” to mean a small coin called a denarius.

Many languages make new letters by changing D a little. Some add hooks or lines so the letter shows a different sound. For example, Ð ð (called Eth) appears in old English and Icelandic; Ɖ ɖ are used in some African languages. Other forms like Đ đ, Ď ď or letters with dots and lines are also cousins made by adding marks.

Linguists have special symbols too. Sounds are shown with letters like ɖ or ɗ, and tiny or raised letters like ᴅ or ᵈ are used when writing about speech sounds. These small changes help match a letter to the exact sound a language uses.

Long ago, letters came from even older signs. The Dalet (𐤃) from ancient Semitic writing is an early ancestor. From Dalet came the Greek letter Delta (Δ δ), and from Delta came the shape used in Coptic writing. A family of related letters spread across Europe.

Those shapes then changed into the Old Italic form and finally into the Latin D we use today. Other alphabets borrowed the idea too: the Cyrillic De (Д д) came from the same family. Even the runic sign dagaz may be a distant cousin showing how letters travel and change over time.

Some signs and symbols look like D or use it to mean something special. The Vietnamese money sign ₫ comes from a D shape and stands for the đồng. In mathematics, a curved symbol ∂ is used for the partial derivative — a way to show how something changes. A plain upright ⅆ is used in some math writing for a small change or a tiny step called a differential.

Short forms also come from D. Old price lists and books use “d.” for a denarius (a penny long ago), and many alphabets make little versions of D for labels, units, and special codes. These symbols show how one letter can become many helpful signs.

Unicode is a system that gives every letter a tiny number so computers can store and show words. The capital letter D has the code point U+0044 and the small letter d is U+0064. Those same numbers also worked in older systems called ASCII and ISO 8859, so many computers and programs agree on the same codes for these letters. Because of these codes, a text file or a website can always know which letter you mean, no matter what device opens it.

Sometimes letters get extra marks, like accents. Some of those are saved as one single code (a "precomposed" form), and others are saved as two codes: the letter plus a separate combining mark. There are also special variant letters that have their own unique codes for certain languages or old-style writing. These choices help computers show letters correctly in many places and styles.