Yiddish orthography is the writing system used for the Yiddish language. It includes Yiddish spelling rules and the Hebrew script, which is used as the basis of a full vocalic alphabet. Letters that are silent or glottal stops in the Hebrew language are used as vowels in Yiddish. Other letters that can serve as both vowels and consonants are either read as appropriate to the context in which they appear or are differentiated by diacritical marks derived from the Hebrew nikud, commonly referred to as "points". Additional phonetic distinctions between letters that share the same base character are also indicated by pointing or by the adjacent placement of otherwise silent base characters. Several Yiddish points are not commonly used in any present-day Hebrew context and others are used in a manner that is specific to Yiddish orthography. There is significant variation in the way this is applied in literary practice. There are also several differing approaches to the disambiguation of characters that can be used as either vowels or consonants.
Words of Aramaic and Hebrew origin are normally written in the traditional orthography of the source language—i.e., the orthography of these words, which is consonant-based, is generally preserved (Niborski 2012). All other Yiddish words are represented with a phonemic orthography. Both forms can appear in a single word—for example, where a Yiddish affix is applied to a Hebrew stem. Yiddish pointing may also be applied to words that are otherwise written entirely with traditional orthography.
In the early 20th century, for both cultural and political reasons, efforts were initiated toward the development of a uniform Yiddish orthography. A specimen initial practice was described in detail by the Yiddish lexicographer Alexander Harkavy in a Treatise on Yiddish Reading, Orthography, and Dialectal Variations first published in 1898 together with his Yiddish-English Dictionary (Harkavy 1898), and available online (beginning with the section headed Yiddish reading). Additional illustrations of this variation are provided in source excerpts in Fishman 1981, which also contains a number of texts specifically about the need (pro and con) for a uniform orthography. A detailed chronology of the major events during this normative action, including rosters of conference participants, bibliographic references to the documents they produced, and summaries of their contents, is given in Yiddish in Schaechter 1999. There is a less detailed (but extensive nonetheless) English language review of this process in Estraikh 1999.