Acronyms in Hebrew use a special punctuation mark called gershayim (״). This mark is placed between the last two letters of the non-inflected form of the acronym (e.g. "report" in singular is "דו״ח," hence the plural "דו״חות"). Acronyms can be formed from strings of single initial letters, e.g. "פזצט״א" pazátsta (for פול, זחל, צפה, טווח, אש), or multiple initial letters, e.g. ארה״ק (for ארץ הקודש, the Holy Land) or ראשל״צ ráshlats (for ראשון לציון, Rishon LeZion).
If the acronym is read as is, then the spelling should be with a final form letter. If, on the other hand, the acronym is read as the complete phrase or read as the individual letters, then it should be spelled with a medial form letter. In practice, this rule is more often than not ignored, and the acronyms spelled either way.
Abbreviations that are truncations of a single word, consisting of the first letter or first several letters of that word (as opposed to acronyms formed from initials or truncations of more than one word) are denoted using the punctuation mark geresh (׳) by placing the sign after the last letter of the abbreviation (e.g. "Ms.": "גב׳"). However, in practice, single and double quotes are often used instead of the special punctuation marks (for which most keyboards do not have keys), with the single quote used both in acronyms and abbreviations.
Often (and especially when they describe a noun), Hebrew acronyms are pronounced by the insertion of a vowel sound (usually [a]) between the letters. These vowels often appear in transliterations to other scripts. Examples include Shas (ש״ס), Tanakh (תנ״ך) and Shabak (שב״כ). There are exceptions to the use of "a", such as Etzel (אצ״ל).
When one of the letters is vav or yud, these may be read as vowels ("u"/“o” and "i") instead: דו״ח (duakh/dokh = דין וחשבון, judgement and account); אדמו״ר (admor = אדוננו מורנו ורבנו, hasidic rebbe; שו״ת (shut = שאלות ותשובות, questions and answers); סכו״ם (sakum = סכין כף ומזלג, knife spoon and fork); תפו״ז (tapuz = תפוח זהב, orange, lit. golden apple); או״ם (um = האומות המאוחדות, the United Nations); ביל״ו Bilu; לח״י Lehi. (An exception is בית״ר, Beitar, pronounced beytar.)
Hebrew numbers (e.g. year numbers in the Hebrew calendar) are written the same way as acronyms, with gershayim before the last character, but pronounced as separate letter names. For example, ה׳תשע״ה (5775 AM, or 2014-2015 CE) is pronounced hei-tav-shin-ayin-hei.
Acronyms have been widely used in Hebrew since at least the Middle Ages. Several important rabbis are referred to with acronyms of their names. For example, Rabbi Shlomo ben Yitzchak is known as Rashi, Rav Moshe ben Maimon (Maimonides) is commonly known as Rambam (Hebrew: רמב״ם), Rabbi Moshe ben Nahman (Nahmanides) is likewise known as the Ramban (Hebrew: רמב״ן), and Baal Shem Tov is called the Besht (Hebrew: בעש״ט).
A number of such acronyms differ only in their last letter. They all begin with "Mahara-", as an acronym of the words ...מורנו הרב רבי (Morenu Ha-Rav rabi ..., Our teacher the Rabbi ...)."
Most often, though, one will find use of acronyms as acrostics, in both prayer, poetry (see Piyyut), and kabbalistic works. Because each Hebrew letter also has a numeric value, embedding an acrostic may give an additional layer of meaning to these works.
One purpose of acrostics was as a mnemonic or a way for an author to weave his name as a signature, or some other spiritual thought, into his work, at a time when much was memorized. Examples of prayers which contain acrostics include:
ישי נוימן, גורמים פגרמטיים, סמנטיים וגרפופונמיים במילוּן קיצורי הכתב, החוג הישראלי לבלשנו ת 18, 2011