The system of writing known as hieroglyphics was used to write the ancient Egyptian language from before 3000 b.c.e. until the late fourth century c.e. Each symbol in this system is known as a hieroglyph. The term hieroglyphic (meaning "sacred writing") was coined by the ancient Greeks, who knew that the Egyptians sometimes called their writing "divine script".

The 500 or so hieroglyphic signs that were in common use can be grouped into three classes: logograms, phonograms, and determinatives. Logograms (also called ideograms) are single signs that represent a complete word. These signs, remnants of the pictographic origins of the system, are relatively few in number.

Far more common are the second class of signs, called phonograms. A phonogram represents not a word but a sound or group of sounds. There are three types of phonograms: those that indicate one, two, or three consonants.

The signs indicating a single consonant may be called "alphabetic", but in fact the Egyptians rarely used only these simple alphabetic signs to write a word. It should be noted that the script indicates only consonants; the vowels would have to be supplied by the reader.

The third class of hieroglyphs is known as determinatives. These signs, of which there are many, have no phonetic value, but rather appear after other hieroglyphic signs (phonograms) to indicate the semantic category of the word.

Determinatives are often very helpful in distinguishing homonyms, which are prevalent due to the lack of vowels in the script. A hieroglyphic text can be written horizontally from left to right or from right to left or vertically from top to bottom.

The use of hieroglyphic script was generally confined to carved or painted inscriptions, most of which were monumental or religious in nature. Already in the Old Egyptian Period (mid-third millennium b.c.e.) the Egyptians used a simplified cursive hieroglyphic script, or, more often, an even more cursive script known as hieratic (from Greek, "priestly"), for texts written with ink. The signs of cursive scripts, especially hieratic, can look quite different from their hieroglyphic counterparts.

By the Late Egyptian Period, beginning in roughly 1600 b.c.e., an even more abbreviated and cursive form of hieratic developed, known as demotic (from Greek, "popular"). With the coming of Christianity to Egypt, many Egyptians adopted the Greek alphabet to write their language.

This adopted script is known as the Coptic alphabet, as is the Egyptian language itself when written in this script. What separates the Coptic alphabet from the Greek is the addition of eight signs, taken over from the demotic script, which were needed to represent sounds not found in Greek.

Almost immediately after the hieroglyphic system ceased to be used (the last known hieroglyphic inscription was made in 394 c.e.), the ability to read it was lost. After this happened it was commonly believed that these symbols did not represent an actual language but were instead a kind of mystical representation of ideas.

It was not until after the discovery of the Rosetta Stone in 1799—on which the same text was written in hieroglyphic, hieratic, and Greek—that scholars were able to decipher the ancient script.