Types of sources:
Primary VS secondary source - A primary source belongs to the person who created it. So let's think about, for example, all of the texts you send. (Yikes, eh?) Your texts are primary sources because you created them. (Diaries or documents or reports created by historical folks are also common forms of primary sources.) Check this out.
Secondary sources involve taking primary sources and making meaning out of them. If your friends decide to take your texts, write out all the stories around those texts, and publish them, they've created a secondary source. Here's some more help with these concepts.
Popular source VS scholarly source - A popular source is designed for a general audience who does not have advanced knowledge of a particular subject. They are used to entertain, inform, and sometimes, to heavily persuade the reader in a biased manner.
A scholarly source is designed for a specific audience who has advanced knowledge of a particular subject, or for those studying that subject. They are used to share findings or developing research in specific areas of study. An excellent chart demonstrating how these differ is located here.