Spelling check is enabled by default in Firefox. But did you know that Firefox doesn't do spell-check everywhere? Yes, it's true. Firefox only does spell-check for input text fields which allow more than one line.

For instance if you are reading this page in Firefox, try entering some text with spelling mistakes into the single line input field below and see for yourself. No spelling mistakes will be highlighted.

Now you might not observe the missing spell-check everywhere. If [ spellcheck="true" ] is used inside the web page html code for the input field, all browsers including Firefox will always do spell-check for that field. To see for yourself, try copying the text you entered earlier into the field below where spell-check has been enabled using html.

Since you won't readily notice whether spell-check is enabled for the text you are typing, chances of spelling mistakes is huge.

How to avoid unnoticed spelling mistakes.

The best way to avoid unnoticed spelling mistakes is to make Firefox do spell-check everywhere. You can do this with the following simple steps -

1. In a new tab, enter "about:config" in address bar.
2. Firefox will ask you to be careful. Just press on "I'll be careful, I promise" button.
3. Type " layout.spellcheckDefault" in the filter field. It will show the value to be set to 1. Double click on the entry and change it to 2.

The possible values are -
0 - Disable Spell check.
1 - Check multi line text boxes only.
2 - Check all text boxes, including single line text boxes.

Please note that once you do this, Firefox will check fields like username or password as well and will highlight every word it finds having a spelling mistake. Although a little inconvenient at first, it will definitely help you avoid spelling mistakes you can't correct later on.