The shapes of the letters correspond to the characteristics of their sounds. Each letter is constructed by a combination of two basic shapes: a vertical stem (either long or short) and either one or two rounded bows (which may or may not be underlined, and may be on the left or right of the stem).
The Tengwar are divided into 4 series, and then a regular set of variants are applied to these initial letters to change the sounds.
The four series correspond to the main place of articulation. Each series is headed by the voicelessless stop consonants for that series. These vary among modes, depending on what sounds the language that the mode is made for requires. For Quenya, they are: c,t,p,qu, and the series are named: calmatéma, tincotéma, parmatéma, quessetéma (téma means "series" in Quenya)
The four basic signs are composed of a vertical stem descending below the line, and a single bow.
A mapping of letters to the sounds of a specific language is called a "mode" (a Tengwar orthography. Some modes use vowel points called tehtar analogous to those used in writing the Hebrew language; other modes, called "full writing" or "Beleriandic" modes, borrow unused consonant signs as vowels. Some modes map the basic consonants to /t/, /p/, /k/, and /k_w/, whilst others use them to represent /t/, /p/, /tS/, and /k/. Some modes follow pronunciation, whilst others rather follow traditional orthography.
Tolkienists have create several Tengwar fonts for various computer systems. A proposal has been made to include Tengwar in the Unicode standard.
Peter Jackson's movie trilogy commencing with The Lord of the Rings: The Fellowship of the Ring features numerous books and artifacts with Tengwar inscriptions, all of which were scrupulously researched for accuracy.
Other conscripts by Tolkien include the Cirth.