How to type underscore (_)
Also called understrike, low line, underdash.
Hold Shift with your left little finger and press the hyphen key with your right little finger. It is the same key as the minus sign, one to the right of 0.
Which finger types _
- Finger
- Right pinky
- Resting position
- ; on the home row
- Shift
- Required, held by the other hand
- Hand
- right
No website can detect which finger you actually used — a browser reports the character, not the hand that produced it. The finger above is the one the standard touch typing layout assigns, and it is the one the lessons here train.
What _ is used for
- Joins words where a space is not allowed, as in file_name or user_id.
- Marks a private or internal name by convention in Python and JavaScript.
- Stands in for a value you are deliberately ignoring in several languages.
- Italicises text in some Markdown flavours.
Where it comes from
It exists because typewriters could not underline. You typed the word, backspaced over it, and struck the underscore key across it — the character was a tool for decorating other characters. Computers made underlining trivial, and the key survived by becoming the space you are allowed to use in a filename.
The mistake people make
Reaching for it with the ring finger. It shares a key with the hyphen at the far right of the number row, and it belongs to the right little finger — the weakest one, stretching the furthest, while the other little finger holds Shift. Both little fingers working at once is why this key is disproportionately slow.
If the key is missing or gives the wrong character
- Windows: hold Alt and type 95 on the numeric keypad.
- Use a hyphen instead in web addresses: search engines treat file-name as two words and file_name as one.
Practise it properly
Knowing which finger owns a key is not the same as using it without thinking. The Typometer course blocks on the wrong key and names the finger for every one, so the habit forms rather than the knowledge.
Other keys
Related guides
Free, and no account needed.
- Start at level 1: the home rowFind F and J without looking, one key at a time.
- How to learn touch typingWhat actually works, what to ignore, and how long it takes.
- The full typing course415 levels from the home row to code and professional documents.
- Untimed typing practicePractise without a clock and focus on the keys you keep missing.