Most anatomy textbooks begin with descriptions of body cavities and body regions. These terms are important for identifying the location of structures. For example, you will fund the lungs within the thoracic cavity, which is the region superior to the diaphragm. The stomach and digestive organs are found in the abdominal cavity, the region below (inferior) the diaphragm.
The dorsal cavity is located on the back side and the ventral cavity is the front region of the human.
As you progress through a course on anatomy, you will be asked to located structures by referencing various regions of the body. The diagram shown below shows the main regions.
Image Source: By Connexions [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0) or CC BY 4.0 (http://creativecommons.org/licenses/by/4.0)], via Wikimedia Commons