Actually Whatsapp tells you, when your message has been successfully sent and just delivered by the other person and that’s the meaning of the tick marks that you see after your message and the first tick mark is to notify you that “the message you sent has been successfully sent” and the second tick mark is for “the message has been successfully delivered to the person”
Their is no such an option until now that tells you whether the other person has read the message, but many user misinterpreted that double check marks next to message is to indicate that a message has been looked at, as many other messaging apps offer you.
Finally now the whatsapp will able to show you if your message is read or not, if the user reads the message then both the tick marks will change into blue colour,
This is the meaning of the tick marks.
After a long a wait now whatsapp updated this option and also confirms that the option is available in updated versions, many people having updated versions have started noticing the tick marks changing into blue colour, this option clears confusions about tick marks that it is not actually the other person read your message until the both tick marks turn’s Blue,
Conclusion- After Blue Check mark update by the whatapp there was many trolls seen in the Social Networking sites.