Read (the beginning of) a message without opening it.

The appearance of “seen” has created a new phenomenon: opening messages partially, having a peek at the beginning of the message and assuming the rest so that the other person doesn’t get a “seen”. Also when writing a message, be aware of how your first sentence begins, because this is what the other person will be halfseening.
When “seen” first appeared some thought they would have to answer messages immediately. But it actually didn’t make the culture of answering change, it only made visible what we already knew: we don’t always reply straight away. Even though it became more acceptable not to reply immediately, the technique of halfseening is very commonly used. Those who don’t find the beginning of the message to be enough but still don’t like to reply straight away may benefit from seen blocking apps.

“I only halfseened his message but I think he wants to ask me out. I’m not going to open it until I think of a reply.”

“She hasn’t seened my message, but she must have halfseened it because Messinger says she was active.”