What is the purpose of creating custom indexes in Salesforce?

Creating custom indexes in Salesforce primarily serves the purpose of improving query performance. When working with large datasets, the efficiency of retrieving records based on certain fields can significantly affect the application's responsiveness and the end-user experience. By creating custom indexes on frequently queried fields, you can help the Salesforce platform locate and retrieve those records more quickly, thus reducing the time consumption for queries and enhancing overall performance.

Indexes enable Salesforce to create a more efficient path to access data, which is especially valuable when dealing with complex queries that might involve filters, sorting, or joining multiple tables. This optimization results in faster response times and a better application experience for users who rely on querying large volumes of data.

While other options touch on related concepts—such as data storage or backups—they do not directly relate to the primary benefit of custom indexes. For instance, creating indexes does not increase the number of records available, nor is it about optimizing how data is stored. The function of assisting with data backups is also outside the purview of what indexes achieve. Thus, the correct answer directly focuses on the performance enhancement aspect provided by custom indexes in the Salesforce environment.