One of the most important pieces of information to look for in a Patent Document is the Patent Classification Number(s) assigned to the particular Patent. The U.S. has recently transitioned to a new classification system, from United States Patent Classification (USPC) to Cooperative Patent Classification (CPC).
This patent has been assigned two CPC numbers. Take note of these numbers, and after looking at several Patents relevant to your invention, identify which CPC numbers have been assigned to multiple Patents.
To find the definition of these CPC numbers, start here:
Classification Search Page
Enter a CPC number and click on Submit.