Defines a recommended header cell width. Use the width CSS property instead, as this attribute is deprecated. The <th> may only be used within a <tr> element. In simple contexts, using the scope attribute on header cells (<th> elements) is redundant because scope is inferred.

⟨th⟩ is used in academic transcription systems to represent letters in south and east Asian alphabets that have the value /tʰ/. According to the Royal Thai General System of Transcription, for example, ⟨th⟩ represents a series of Thai letters with the value /tʰ/.

Latin Th digraph. Th is a digraph in the Latin script. It was originally introduced into Latin to transliterate Greek loan words. In modern languages that use the Latin alphabet, it represents a number of different sounds. It is the most common digraph in order of frequency in the English language.

In some Middle English manuscripts, ⟨th⟩ appears for ⟨t⟩ or ⟨d⟩: tho 'to' or 'do', thyll till, whythe white, thede deed. In Modern English we see it in Esther, Thomas, Thames, thyme, Witham (the town in Essex, not the river in Lincolnshire which is pronounced with /ð/) and the old spelling of Satan as Sathan.

The spelling ⟨th⟩ commonly produces 2 sounds in English pronunciation /θ/ and /ð/. Both are fricatives and made with the tongue behind the teeth: /θ/ is voiceless, it is made only with air, whereas /ð/ is voiced; it is made with vibration of the vocal cords. Some examples of words with each sound are:

Thorium, radioactive metallic chemical element, chemical symbol Th, atomic number 90, one of the actinoid series of elements.