Many Jews and Jewish scholars consider certain Hebrew names for G-d so holy that, once written, they cannot not be erased or destroyed. Some people even take caution when writing in other languages or online.
The most common name of G-d in the Hebrew Bible is the Hebrew word יהוה, usually written as “YHWH” in Roman letters. However, this is considered too sacred to speak and is usually pronounced as Adonai (my Lord) in prayers.
In everyday talk, many Jews consider Adonai too holy to use. Instead, they use the term HaShem (“the Name”) to refer to G-d. There are also many other names for G-d in the Hebrew Bible.
Text adapted from English Wikipedia, Creative Commons Attribution-ShareAlike License 4.0.
Textile with the name YHWH Swedish National Heritage Board via Wikimedia Commons, Public Domain.