Certhas Daeron was created by Daeron, the minstrel of king Thingol of Doriath and was later expanded into what was known as the Angerthas Daeron. Although the Cirth were later largely replaced by the Tengwar (which were enhanced and brought by Fëanor), they were adopted by Dwarves to write down their Khuzdul language (Angerthas Moria and Angerthas Erebor) because its straight lines were better suited to carving than the curved strokes of the Tengwar. Some examples of Cirth writings are the inscription on Balin's tomb in Moria and the inscriptions on the title page of The Hobbit and on the top of the title pages for The Lord of the Rings.
Cirth is plural and is written with a capital C when referring to the writing system—the runes themselves can be called cirth. A single rune is a certh.
Many letters have shapes also found in the historical Futhark, but their sound values are only similar in a few of the vowels. Rather, the system of assignment of sound values is much more systematic in the Cirth than in the historical runes (e.g., voiced variants of a voiceless sound are expressed by an additional stroke). A similar system has been proposed for a few historical runes (e.g. p ᛈ and w ᚹ as variants of b ᛒ), but is in any case much more obscure.
The Cirth are not part of the Unicode Standard. However the ConScript Unicode Registry has defined the U+E080–E0FF range of the Unicode "Private Use Area" for Cirth.