How to Use the Onscreen Keyboard in OS X Yosemite
Many OS X power users overlook one alternative method of input: the virtual keyboard, which you can click with your mouse or trackpad to type text in a document, in a System Preferences field, or in anything else that needs completing.
To display the onscreen keyboard, choose System Preferences→Keyboard→Keyboard tab, and then select the Show Keyboard & Character Viewer in Menu Bar check box.
Close System Preferences and click the Input Menu icon that appears in your Finder menu bar — the icon looks like a square containing an asterisk or a country’s flag — and choose Show Keyboard Viewer. You can type by clicking this floating keyboard’s buttons, including all the navigation and cursor control keys. To hide the keyboard, just click the Input Menu icon in the menu bar again and choose Hide Keyboard Viewer, or click the Close button on the keyboard viewer.
To enter special symbols in a document, click the Input Menu icon in the Finder menu bar and choose Character Viewer — you can select just the right graphics character from a huge selection of symbols, including emoji (also called emoticons), arrows and bullets, pictographs, currency and even math symbols!