What does this mean?- can't verify identity

[AceC]

Whenever I am on reputable websites that I always use, this security thing pops up (attached photo). It most recently happened on yahoo. Just wondering what this is, and if I should be concerned?

 

[snaky69]

Whenever I am on reputable websites that I always use, this security thing pops up (attached photo). It most recently happened on yahoo. Just wondering what this is, and if I should be concerned?

It happens when the webmaster forgets to update his security certificate or said certificate expires.

If you are browsing a known safe site (such as Yahoo), then you shouldn't worry.

On more shady websites, I'd be leary.

 

[monokitty]

Make sure the Date & Time on the computer is correct as well.