Cirth (also “Certhas”, Sindarin word for “runes”) is a writing system invented by J.R.R. Tolkien for his fictional languages. The original Certhas were invented in The First Age by Grey Elves of Beleriand to better suit for carving and engraving on wood, stone or metal, than Tengwar. Single rune of Cirth is called “certh” in Sindarin, and unlike Tengwar vowels have their own runes. Cirth had runes for Quenya, but I'm unaware of any Cirth inscription in this language. By the Second Age Cirth were rarely used by elves, but became popular among Dwarves and later Men.

The Cirth in their older and simpler form spread eastward in the Second Age, and became known to many peoples, to Men and Dwarves, and even to Orcs, all of whom altered them to suit their purposes and according to their skill or lack of it. (LOTR III, Appendix E, II: Writing)

Then Nár turned the head [of Thrór] and saw branded on the brow in dwarf-runes so that he could read it the name AZOG. (LOTR III, Appendix A, III: Durin's Folk)

But in the chapter “The Departure of Boromir” this passage contradicts the quotes above:

on the front of their iron helms was set an S-rune, wrought of some white metal.
   ‘I have not seen these tokens before,’ said Aragorn. ‘What do they mean?’
   ‘S is for Sauron,’ said Gimli. ‘That is easy to read.’
   ‘Nay!’ said Legolas. ‘Sauron does not use the elf-runes.’

So I assume, that Cirth was used by Westron-speaking orcs of Misty Mountains (as Azog) and Isengard (‘S is for Saruman, I guess,’ - said Aragorn later).

Westron used a variant of Cirth called “Angerthas Erebor” invented in the beginning of Third Age, when Thráin I driven from Moria moved to Lonelely Mountain and established his kingdom there.

Unlike Tengwar, Cirth is not so well organized into phonetical series (there is less correspondence between shapes of letters and their phonetical value). There are 60 basic runes and over 50 additional glyphs or modifications of basic runes in three major versions (Angerthas Daeron, Angerthas Moria, Angerthas Erebor).

While orcs probably used simplified Angerthas Erebor variant for their Debased Black Speech and Westron-Orkish pidgins, older versions contain runes better suitable for Classical Black Speech phonetics, so I've decided to include them too. However, many additional runes for diphthongs (ai, au, oi) and consonant clusters frequently used in Black Speech (like zg or sk) are not used for several reasons:

• Additional runes have very different meaning in various versions of Cirth;
• Black Speech have a large number of consonant clusters, there is no reason for making separate runes for only few of them, especially when the most frequent one rz is missing anyway;
• Not all fonts have additional runes;

Shorter version of this table containing only runes used in Nûrlâm is presented at the end of this article.

Diacritics were introduced in Angerthas Erebor. They present only in Dan Smith's fonts.

* only for demonstration purposes

Nûrlâm do not use long consonants, but circumflex may be used for nasalized consonants (mb, mp, nt, nd, nk, ng) instead of dedicated runes. Macron below is the preferred way of expressing long consonants to avoid confusion with other Cirth modes.

Unfortunately, we don't know the complete numerical system of Cirth. The only source that has numbers is the Book Of Mazarbul, and it has only 1, 3, 4, 5 and 6.

Probably under-dots should be used not only for number 4, but for other digits too.

The following characters may be used as punctuation marks (without conventional meaning) or for decorative purposes. Usually single middle-aligned dot represent a space character, and every additional dot is used to denote a longer pause.

Orcish curse “Uglúk u bagronk sha pushdug Saruman-glob búb-hosh skai” will look like this in Cirth:

• Cirth at Wikipedia
• Cirth at Tolkien Gateway
• BSSScribe – Nûrlâm's official transcriber (see also documentation page)
• Glǽmscribe – The Tolkien language transcriber
• Tengwar