You will find a small green color lock icon in URL tab. Most of the https enabled sites uses SSL connection. Even if someone will gain access to the encrypted data, he can't be able to decrypt it and thus your information is safe. It creates a secure connection between a client (or browser) and a server. To fill this vulnerability, SSL was introduced which encrypts the data before transmission.
Normally when you enter confidential information like your username, password or credit card number, then the data is transmitted in a plain text which is very easy to hack.
It's an extra security layer which keeps all your data private and safe. " Your connection is not private" or " NET::ER_CERT_DATE_INVALID" error occurs due to the SSL error basically. Why this connection privacy error occurs in Google Chrome Here's a detailed information on this topic. If you are also facing the same problem, then you might be worrying a little as it is concerned about your privacy and you wants to fix it as soon as possible. Somehow, I managed to remove this error from Google Chrome. It comes as a surprise to me that how Google like giant website can show this privacy warning. Moreover, the https of URL is marked in a red color with warning sign left to it (See in above picture). NET::ER_CERT_DATE_INVALID There is a red color lock icon on screen with cross symbol on it. Attackers might be trying to steal your information from (for example, passwords, messages, or credit cards).