WhatsApp is a fantastic service for letting you chat with and send picture- or video messages to your contacts for free over a data connection without using up your tariff allowances. Now it's possible to send any document up to 100MB for free, too. Also see: How to make video calls and group video calls on WhatsApp.
The Documents feature should now be available to all WhatsApp users, and the most recent update for Android and iPhone (rolling out now) lets you share files other than simple PDFs.
You can update WhatsApp on an Android phone by launching Google Play and clicking the three horizontal lines icon at the top left of the page, then choosing My apps & games and checking to see whether a WhatsApp update is available. If it is, tap on the app to launch it, then tap Update and accept any new permissions. Also see: How to avoid WhatsApp scams, viruses and hoaxes.
How to send documents on WhatsApp
• Launch WhatsApp and tap on an ongoing conversation in the Chats tab to open an existing thread, or tap on a contact in the Contacts tab to start a new conversation.
• Tap the paperclip icon at the top right of the screen to add an attachment to your message.
• You'll see six icons pop up, the first of which is 'Document'.
• Tap the Document icon. WhatsApp will bring up a list of documents stored on your phone.
• Select a document by tapping on it. To send press Send in the pop-up window.