Geocoding is the process of transforming location information (e.g., street addresses, place names, etc.) into geocoordinate data (e.g., latitude/longitude) that can be plotted and symbolized on a map.
Reverse geocoding is the process of taking latitude and longitude values from a map layer and converting them into street addresses or place names.
There are a number of browser-based geocoding tools that can be used if your research project doesn't include sensitive data (e.g., HIPAA, personally-identifiable data, etc.) If you are working with sensitive data, we recommend that your create your own address locator to run within a secure environment.
To geocode, you will need to have access to an address locator with the appropriate reference data. The following resources can help guide you through the process of creating an custom address locator for geocoding.