Today WhatsApp (iOS, Android), used by approximately 1 billion people worldwide, announced end-to-encryption throughout its network, for all types of messages (texts, videos, phone calls) shared within its app. With end-to-end encryption, even the company itself cannot view the contents of your communications. All the bits sent from one WhatsApp user to another are scrambled in a way that cannot be unscrambled by anyone except the sender and the recipient.
This upgrade does not require you to update the app itself (in fact, no new version of WhatsApp has come out in several days). It takes place on the server side. So as long as there is a version of WhatsApp that's compatible with your device, you will benefit from this change whenever you use the app, and your messages are encrypted whether your network is Wi-Fi, 4G LTE, 3G, or Ethernet.
WhatsApp makes its case for privacy
WhatApp's blog does not mention Apple or the FBI by name, instead saying, "Recently there has been a lot of discussion about encrypted services and the work of law enforcement. While we recognize the important work of law enforcement in keeping people safe, efforts to weaken encryption risk exposing people's information to abuse from cyber criminals, hackers, and rogue states." CEO Jan Koum adds, "The desire to protect people's private communication is one of the core beliefs we have at WhatsApp, and for me, it's personal. I grew up in the USSR during communist rule, and the fact that people couldn't speak freely is one of the reasons my family moved to the United States."
Other options for encrypted messaging
WhatsApp is not the only messaging app to receive end-to-end encryption. For example, Signal Private Messenger (iOS, Android) (originally known as RedPhone) has had that security feature from the beginning. But WhatsApp has by far the biggest reach of your available end-to-end encryption options.
The Electronic Frontier Foundation has a privacy scorecard for messaging apps, some of which are still technically more trustworthy than WhatsApp, due to its lack of independent code review. Apps that skip independent review generally do so to protect their trade secrets.