Common threats
These are some common threats people face when they're thinking about defending their privacy and security. You may be concerned with none, one, a few, or all of these possibilities, and the plan you make depends on what your individual goals are.
7. Privacy from service providers
We live in a world where almost everything is connected to the internet. Our "private" messages, emails, and social interactions are typically stored on a server, somewhere. Generally, when you send someone a message it's stored on a server, and when your friend wants to read the message the server will show it to them.
The obvious problem with this is that the service provider (or a hacker who has compromised the server) can access your conversations whenever and however they want, without you ever knowing. This applies to many common services, like SMS messaging, Telegram, and Discord.
Thankfully, E2EE can alleviate this issue by encrypting communications between you and your desired recipients before they are even sent to the server. The confidentiality of your messages is guaranteed, assuming the service provider doesn't have access to the private keys of either party.
Even with E2EE, service providers can still profile you based on metadata, which typically isn't protected. While the service provider can't read your messages, they can still observe important things, such as who you're talking to, how often you message them, and when you're typically active. Protection of metadata is fairly uncommon, and—if it's within your threat model—you should pay close attention to the technical documentation of the software you're using to see if there's any metadata minimization or protection at all.