Besiyata Dishmaya (Aramaic: בסיעתא דשמיא) is an Aramaic phrase, meaning "with the help of Heaven". The acronym BS"D (Mostly written in Hebrew: בס"ד) has become a popular term among Orthodox Jews, reproduced at the top of every written document (beginnings of correspondences, letters, notes, etc.) as a reminder to them that all comes from God, including the following content, and to contextualize what is really important in the text, that without God's help, nothing can be done successfully. BS"D is not derived from any religious law of the Halakha, but it is considered an old accepted tradition.
The reason for the common use of the three-letter abbreviation, בס"ד (BS"D), is probably because it does not contain the Hebrew letter Hei (ה), that is used to imply the name of God, and for this reason, a page which contains the letters בס"ד (BS"D) without any other Torah content does not require Genizah (a process for writings that contain the name of God), and thus can be thrown away without a fear of violation.
Other languages, according to Judaism, are not considered the same as the sacred language (Lashon HaKodesh) (Hebrew), the language with which God created the earth and used to decide how he would be named, and therefore have no such restriction.
The book Toldot Yitzhak (The Offspring of Isaac), by Yitzhak Karo offers the meaning of this custom of writing ב"ה (B"H), at the top of every letter, with accordance to the biblical verse: "In all thy ways acknowledge Him, and He will direct thy paths" (Book of Proverbs 3:6)."
- In Israel's declaration of independence, Yehuda Leib Maimon added the abbreviation בעז"ה (Hebrew: בעזרת השם, B'ezrat HaShem, "with God's help") before his name, so that God's name will appear in the document.
- In his book Mac OS X and iOS Internals: To the Apple's Core, Jonathan Levin named his BSD related chapter (Chapter 13): BS"D - The BSD Layer as allusions to his Jewish roots and to Mac OS X needing the help of a greater power (its BSD core) to get to where it did.
- Tofutti products feature the Hebrew expression on the side of all their packaging.
- New York's famous B&H camera superstore is named after the acronym B"H (Hebrew: ב"ה) also read as "Baruch HaShem", "Thank God". 
- "אזכרת שמות". Yeshiva.org.il. Retrieved 2011-01-31.
- "What does B"H mean? - The Details". Chabad.org. Retrieved 2011-01-31.
- "אחד המאבקים על זהותה היהודית של מדינת ישראל בעת הקמתה". Retrieved 2012-11-11.
- Levin, Jonathan (2012). "Table of Contents". Mac OS X and iOS Internals: To the Apple's Core (1st ed.). Wrox. ISBN 1118222253.
- "New York's B&H camera shop mixes Yiddishkeit and hi-tech savvy". Retrieved 2018-04-08.
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