what does blue check marks in whatsapp means?

[George]

when I send msg to any of my whatsapp friends the check mark turns blue from grey, does anyone else is getting the blue check marks?
if yes then what does that mean?

 

[tarushi1]

that means your message is read..

 

[om2580]

yes it means your msg has been read

 

[Olin Lamanna]

Two blue ticks means message was read. If you press and hold on the message with the blue tick and tap info.