OS X El Capitan: Use the Character Viewer
Open the Character Viewer: In a document, choose Edit > Emoji & Symbols, or press Control-Command-Space.
If you previously used the Character Viewer, or set the option in Keyboard preferences to show it in the Input menu, you can also open it from the Input menu.
To open Keyboard preferences, choose Apple menu > System Preferences, click Keyboard, then click Keyboard.
Expand or collapse the Character Viewer: Click the expand or collapse button in the upper-right corner of the viewer. You may need to scroll to the top of the viewer.
Browse characters and symbols: Click the buttons across the bottom of the viewer (if it’s collapsed) or along the left edge of the viewer (it it’s expanded). When the viewer’s expanded, additional categories are visible.
If you don’t see a character or symbol, try searching for it by the Unicode name (such as Question Mark) or code (such as U+003F).
For some emojis, such as those for people, you can hold down an emoji to see variations of it.
Insert a character or symbol in a document: Position the insertion point in the document where you want the item to appear, then click the item in the viewer. If the viewer’s expanded, double-click the item.
Make a symbol or character a favorite: Expand the viewer, select an item, then click Add to Favorites. Or drag the item onto Favorites (if shown) in the sidebar.
Customize the Character Viewer: Expand the viewer, then click the Action pop-up menu You can make the symbols larger so they’re easier to see. To change the categories shown in the viewer, choose Customize List, select or deselect categories, then click Done.
If an app doesn’t use Unicode (a worldwide character set that works with most languages), you may not be able to type some special characters and symbols. Try inserting a different character or using a different app.