The online messages that can be read by your boss
A European court has ruled that companies are allowed to monitor workers' online chats.
It's after judges said a firm that read a worker's Yahoo Messenger chats, sent while he was at work, was within its rights.
So where do you draw the line with personal messages at work?
"Well it would depend on the policy," explains Felicity Carroll from A City Law Firm.
"If the policy had a blanket rule that no social media was to be used, or no personal messages would be sent during work hours and that was breached - that would give your employer grounds to build a case against you."
Felicity says the arrangement is simple; on agreeing to a contract you agree to your employer's rules, and they in turn agree to pay you. So read the small print.
But there are still barriers to protect your privacy.
"They wouldn't be able to then go into your Facebook or log in as you and look at your messages, as that would go beyond the policy, she explains.
"That's your personal use."
Ben Wilmot is head of policy at the CIPD, which represents people in HR departments.
"There does need to be a bit of give and take. Digital technology means we are seeing blurring between work and home.
"Employers need to be very clear about what they do allow, and individuals need to ensure they comply with the rules employers do have."
Felicity thinks it's worth staying on top of your social media too.
"I think Facebook is a very blurred area there's not enough law in relation to that at the moment.
"Because it's a public domain your employer does have access to that. Even if they're not a friend with you.
"The law does permit the employer to use information that's used on social media, that's used on Facebook, within their ability to use that as evidence."