In this example, we will use Linux Mint 17.3 and gedit. Start with an empty document.
At the cursor, press the Shift + Ctrl + u key combination, and you will see a lowercase, underlined u. This indicates that you can now enter a Unicode character by entering its code.
Enter the code of the character you wish to display. In this case, we want a black star, which is Unicode code 2605. Enter 2605.
Press the Enter key. The corresponding character should appear if it is supported by the current font.
You can insert Unicode symbols anywhere in your text. Simply enter the Shift + Ctrl + u key combination at the point where you need the Unicode character.
“How do I know which Unicode codes to use?”
Unicode has a vast number of characters, so the only way to find a certain character’s code (besides memorization) is to consult an online Unicode chart and look it up.
Note that when you enter a Unicode code from the keyboard as shown above you are entering the hexadecimal value, which is denoted by U+2605 in the Unicode page listings.
For example, Unicode provides a set of arrows. In the previous example, we locate the arrow we wish to use and find out that it is a Rightwards Arrow and its Unicode value is U+2192. We press Shift + Ctrl + u and enter 2192.
Suppose we want to use the Skull and Crossbones character. Its Unicode value is U+2620.
Keep in mind that your current font must support the character you wish to display. Not all fonts support all Unicode characters, and this can vary across operating systems.
Linux has superb Unicode support, so this should not be much of an issue in Linux systems for most of the standard fonts.
Also note that this technique is not limited to a text editor. You can enter Unicode values at the command line, a browser search box (this can produce some interesting results!), or wherever text can be entered.