A locator is a portable file that is used to perform geocoding across the ArcGIS platform. Locators contain a snapshot of the reference data that is used for geocoding, as well as indexes and local addressing knowledge that help return the best match during the geocoding process. A locator can be accessed as a service, such as the ArcGIS Online World Geocoding Service, as a file on disk to perform local desktop geocoding, or within a mobile map package for use with mobile applications.
Why locators are used
A locator can help you navigate to a specific location on the map or generate point features from tables of addresses or places. The results of geocoding can be used to perform spatial and tabular analysis to help make specific decisions for or within your organization. Locators provide specialized indexes, rules, configuration, and regional knowledge that allow a more sophisticated approach to search as opposed to only performing a database query. A locator can be fine-tuned to help return the best match results possible for your needs.
How and when locators are used
Locators accessed from a file folder on your desktop machine or as a locator service hosted in ArcGIS Enterprise can be used in ArcGIS Pro. When a locator is packaged as part of a mobile map package, it can be used on a mobile device in an application such as Navigator for ArcGIS. The locator service can also be used when geocoding functionality is needed in a web application such as Web AppBuilder for ArcGIS. Since the locator is a portable file, it can be distributed throughout your organization on a file share or shared outside of your organization via ArcGIS.com when in the form of a locator package.