Understanding the term "depth of field" can be tricky sometimes, however it's important to get a grasp on the definition as soon as possible. In short, this term means the area of your photo that is in focus. A big thing to keep in mind when debating how to adjust your depth of field is this:
"The key to mastering photography is not to follow the rules but to
understand them. Understanding the photographic principles that define
photography is a barrier that must be broken to truly unlock your full
potential as a photographer. The problems that plague beginners are the same problems faced by the
pros, that is controlling your image with the exposure triangle;
shutter speed, aperture, and ISO. This article will focus on
understanding depth of field (DOF)" (Lockhart, PetaPixel). To read more on Lockhart's article and check out the video tutorial, click "here".
Lockhart, Jodan. "Understanding Depth of Field: How Aperture Affects DOF, Visualized." PetaPixel RSS. N.p., 17 Feb. 2015. Web. 23 Feb. 2015.