Alternatively referred to as a low line, low dash, and understrike, the underscore ( _ ) is a symbol found on the same keyboard key as the hyphen. The picture to the right is an example of an underscore at the beginning and end of the word "Underscore."
Where is the underscore key on the keyboard?
Below is an overview of a computer keyboard with the underscore key highlighted in blue.
How to create the '_' symbol
Creating the '_' symbol on a U.S. keyboard
Creating the '_' symbol on a smartphone or tablet
What is an underscore used for on a computer?
The underscore is commonly used as an alternative to the space key when a space is not allowed. For example, in computer programming, a variable may be named $my_variable, using an underscore instead of a space because spaces are not permitted in a variable name.
Underscore vs. underline
An underscore is different than an underline. If you are trying to underline any letter, number, or other text, the underline feature should be used. The underscore, by contrast, takes the place of another character, like a number, letter, or symbol; it cannot be used under another character.
Underscore in file names
It is not uncommon to use an underscore in a file name in place of a space, especially on the Internet. However, if you're concerned about SEO or have a web page with images or other files, we suggest using a hyphen instead of an underscore when separating keywords. Google treats an underscore as a combiner and a hyphen as a separator, so "computer_hope" is treated as "computerhope" and "computer-hope" is treated as "computer hope."