Underscore Sign

Rules and Examples

Punctuation marksThe underscore sign is mainly used to show a space where a space is not allowed, such as in internet usernames, email addresses and some computer programs.

Click Here for Step-by-Step Rules, Stories and Exercises to Practice All English Tenses

Click Here for Step-by-Step Rules, Stories and Exercises to Practice All Tenses

The underscore looks like a dash below the letters ( _ ).

The underscore sign is also called:
  • understrike

  • underbar

  • low line

  • low dash

  • underline

  • underdash

On the keyboard

To make an underscore on most keyboards, hold the SHIFT key and press they hyphen/underscore key to the right of the zero (on the top number line).


The underscore sign was originally used on typewriters to underline words. On a typewriter, you would first type the word then move back to the beginning of the word and underline it with the underscore key.


Rules for using the underscore sign

1. Use multiple underscores to create blanks.

To create a long line with the underscore key, hold SHIFT and press the underscore key repeatedly until your line is the correct length.


  • Please sign here ______________________

  • I, _____________________, promise to complete my chores by Friday.

  • Fill in the blanks with there, their or they're:

    1. _____ going to the zoo tomorrow.

    2. Jill wants to go to _____ house.

    3. Please put the book over _____.

    4. _____ you are!

    5. Which one is _____ car?

    6. Do you know what _____ serving for lunch today?

In the six examples above, we created the longer lines by pressing the underscore key five times.

woman on computer

2. Use the underscore sign in place of spaces in email addresses and usernames.

The underscore sign can be used in usernames and email addresses to make them unique and sometimes easier to read.

Do not put spaces before or after an underscore when using it in email addresses and usernames.

Without the underscore sign:

[email protected]

With the underscore sign:

[email protected]

Without the underscore sign:

[email protected]

With the underscore sign:

[email protected]

  • [email protected]

    This email address would read: john underscore doe at my mail dot net.

  • [email protected]

    This email address would read: sandy underscore heart underscore nineteen fifty-seven at gmail dot com.

  • [email protected]

    This email address would read: ask underscore the underscore teacher at my school dot net.

at sign


If you create a hyperlink on an email address that includes underscore signs, the underscore signs will look like part of the hyperlink line.

When you click on a working hyperlink it takes you directly to a specific website or address.

Without hyperlink:

[email protected]

With hyperlink:

[email protected]

You cannot see the underscore in the above example.

However, you know there is an underscore because email addresses and usernames cannot contain spaces.

These were the uses of the underscore sign. Now that you know them, it is time to practice! Read and do exercises.

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