A custom setting is primarily used to store what kind of data in Salesforce?

A custom setting in Salesforce is primarily used to store configuration data. This type of data is essential for your applications and can be accessed easily through code or formula fields, allowing for dynamic configuration without the need for hard coding values.

Configuration data stored in custom settings can vary from user preferences to application settings that dictate how various features behave. It enables developers and administrators to create reusable and easily modifiable settings that can adapt to various environments or user needs without altering the core code or functionality of Salesforce.

Other options, such as static code, user records, and system logs, do not align with the purpose of custom settings. Static code refers to fixed values in the code that do not change, user records pertain to individual users in the system, and system logs track system performance and issues, rather than serving as a long-term configuration tool. Custom settings fill the gap of needing a flexible and customizable way to handle application and configuration data.