Happy Face

• A happy face, with a colon followed by a right parenthesis and sometimes a dash for the nose, is the most common emoticon. In personal communication, you can use it whenever you'd naturally smile if you were talking face-to-face. A happy face is only appropriate in messages with a friendly tone, so it's not appropriate when you're trying to tone down an aggressive or angry message. A good example of how to use a happy face effectively is when you're a supervisor assigning tasks to a new employee. Just adding a happy face to your email message can put them at ease and make them see you in a positive light.
  
  

Open-Mouth Happy Face

• When you want to ramp up the enthusiasm and positivity in your message, it's time for the open-mouth happy face. It has a colon followed by a capital "D" and it's a good choice if you're asking someone for a favor or celebrating something that happened to you or them. It's also appropriate when you're telling a joke or paying a compliment. You can even use it to let others know that you're only trying to help, when you correct their mistakes; only do this with people you know.
  
  

Sad Face

• A sad face is identical to a happy face, except the parenthesis is reversed. This emoticon can be interpreted as sarcastic or insensitive, so you need to be careful how you use it. One situation where it's generally safe is when you're trying to express you're more unhappy with yourself than others. Don't use a sad face to ask for help, or others might think you're incompetent or pathetic. If you're sad in a non-aggressive way, a sad face can show empathy for others or get them to feel empathy for you. It can also come across as sarcastic, if it doesn't match your message.
  
  

Face With Tongue Out

• This emoticon has a colon with a capital "P," and it's hard to use appropriately, as it's rarely appropriate to stick your tongue out at someone. Since a "tongue out" expression is associated with mocking or ridicule, it's easy for others to take it the wrong way. For this reason, it's best to limit "tongue out" emoticons to lighthearted conversations where silliness is the dominant theme. If you're sharing tongue-in-cheek humor, or playfully engaging in a battle of wits with a friend, a "tongue out" emoticon can add to the fun. If you're not, it can seem sarcastic or even downright weird.