End-to-end encryption is a system of communication where messages are encrypted on your device and not decrypted until they reach the intended recipient. This ensures that any actor who intercepts traffic cannot read the message contents, nor can anybody with access to the central servers where data is stored.

If code is open source then it can be independently examined and audited by anyone qualified to do so, to ensure that there are no backdoors, vulnerabilities, or other security issues.

When selecting an encrypted messaging app, ensure it's fully open source, stable, actively maintained, and ideally backed by reputable developers.

Enable security settings, including contact verification, security notifications, and encryption. Disable optional non-security features such as read receipt, last online, and typing notification.

Your conversation can only be as secure as the weakest link. Often the easiest way to infiltrate a communications channel is to target the individual or node with the least protection.

Some mobile messaging apps offer a web or desktop companion. This not only increases attack surface but it has been linked to several critical security issues, and should therefore be avoided, if possible.

The risk of compromise rises exponentially, the more participants are in a group, as the attack surface increases. Periodically check that all participants are legitimate.

There are several stages where your digital communications could be monitored or intercepted. This includes: your or your participants' device, your ISP, national gateway or government logging, the messaging provider, the servers.

In certain situations, it may be worth making a communication plan. This should include primary and backup methods of securely getting in hold with each other.

Metadata is "Data about Data" or additional information attached to a file or transaction. When you send a photo, audio recording, video, or document you may be revealing more than you intended to.

Sending links via various services can unintentionally expose your personal information. This is because, when a thumbnail or preview is generated- it happens on the client-side.

Always ensure you are talking to the intended recipient, and that they have not been compromised. One method for doing so is to use an app which supports contact verification.

Self-destructing messages is a feature that causes your messages to automatically delete after a set amount of time. This means that if your device is lost, stolen, or seized, an adversary will only have access to the most recent communications.

SMS may be convenient, but it's not secure. It is susceptible to threats such as interception, sim swapping, manipulation, and malware.

Be wary of messaging applications with trackers, as the detailed usage statistics they collect are often very invasive, and can sometimes reveal your identity as well as personal information that you would otherwise not intend to share.

The jurisdictions where the organisation is based, and data is hosted should also be taken into account.

If you believe you may be targeted, you should opt for an anonymous messaging platform that does not require a phone number, or any other personally identifiable information to sign up or use.

Opt for a platform that implements forward secrecy. This is where your app generates a new encryption key for every message.

If all data flows through a central provider, you have to trust them with your data and meta-data. You cannot verify that the system running is authentic without back doors.