If you have spend much time around #wordpress, then there is a good high probability that you have come across the term “WP_Query before. However, if you are totally new to the concept, then let us guide you through it.
WP_Query is a #php class that has certain properties but it contains a lot of powerful behavior. Some of the things you need to understand about WP_Query is that by default, when you just say new WP_Query, you don’t get much use from it. Rather, you get most of the value from WP_Query from understanding how to initialize it correctly.
If you are interested in learning more about it, here’s a beginner’s guide to WP_Query: http://wpshout.com/getting-know-wp_query/