Am I using data that I don't have?

[AC Question]

When I use wi-fi on my Samsung Galaxy s6, it puts it under data usage. The blue bar also has been decreasing. It also increases how many "MB" I have used. Is this a bad thing? I don't have a plan or anything as I have just bought the phone by itself. Thanks for any help!

 

[belodion]

Are you reading mobile data usage or wifi data usage? Data is used for both. You don't need a mobile data plan to use data over wifi.