(This how-to is based on my experiences and info on Apple’s support pages - where the images come from. Then, hold Command-V to paste the character or word repeatedly. If a key isn’t designed to repeat in the app you’re using, copy the character to the clipboard. To do this, click on the Apple menu in the menu bar, then navigate to System Preferences > Language & Text > Input Sources and select the Keyboard & Character Viewer tickbox. If a character isn’t repeating, check the Keyboard pane of System Preferences to make sure that the Key Repeat slider isn’t set to Off. In apps where accented characters aren’t used-like Calculator, Grapher, or Terminal-letter and number keys also repeat when you hold them down. Hold down the Space bar or symbol keys (like hyphen or equals) to make these characters repeat in most apps. Some keys repeat when you hold them down, depending on where you type them. The menu also doesn’t appear when the Key Repeat slider is set to Off in the Keyboard pane of System Preferences. If no additional characters are available for the key you’re holding, the pop-over menu doesn’t appear.
If you decide you don’t want to type an accented character after holding a key, type another character, or press the escape (esc) key. To choose one of the characters displayed, type the number that appears under the character, or click the character you want to use. To type an accented or alternate version of a character, hold a key down until its alternate characters are displayed. If you just send a few emoji without any other text, the emoji appear three times larger. With macOS Sierra, emoji you send in Messages appear at the same size as the text they’re part of. In the Messages app, you can also see the Character Viewer pop-up when you click the grinning face icon. Characters and symbols you use often appear in the Frequently Used list in this window. When you find the character you want, click it to insert it into your text.
Use the search field at the top of the window, or click the symbol icon (shown below to the right of the search field) to expand the window and reveal more characters: The Character Viewer pop-up window appears: Click the place in your document or message where you want the character to appear. You can use the Character Viewer to insert smileys, dingbats, and other symbols as you type. macOS Sierra includes features that make it easy to find and type special characters and currency symbols. You can do fun things with your Mac, such as typing accents, emojis and symbols.