For those of you who do not know, WhatsApp is an alternative texting app for smartphones. With a WiFi connection It works with any type of smartphone unlike iMessage which only works with iPhones. Another advantage over iMessage is that it has an easy way to save a transcript of your chats (to do so with iMessage you need to use a third party app like iBackup Viewer.)
To save a transcript of a chat in WhatsApp:
1) Open the Chat you want to save.
2) Scroll up to the top of the chat.
3) Select Info.
4) Select Email Chat.
5) Mail it to yourself and you will receive a .txt file with the entire chat stream.
Too bad iMessage is not so easy.