Salesforce Platform Developer Practice Exam 2025 – All-in-One Guide to Ace Your Certification!

In Apex, a Set is a collection type specifically designed to hold unique values. This means that any value added to a Set automatically eliminates duplicates. When you add an element that is already present in the Set, it will not be added again, keeping the collection's integrity intact.

This property of Sets is particularly useful in scenarios where you want to maintain a collection of distinct items, such as tracking unique identifiers, ensuring that no duplicate entries are processed, or avoiding repetition of data during operations like comparisons.

On the other hand, other types of collections, such as Lists and Maps, do not inherently ensure uniqueness. Lists can contain duplicate values, and while Maps can hold unique keys, the values associated with those keys can still be duplicated. An SObject is used to represent a single record in Salesforce and does not function as a collection in the same way as the others. Enums are a special data type that represents a fixed set of constants and are not collections at all.