Explain what a collection data structure is and how it is used in programming.

A collection is a data structure that stores a set of elements and provides methods for adding, removing, and iterating over them. In programming, collections are used for convenient management of groups of objects.

Examples of collections:

• Lists — ordered sets of elements.
• Sets — unique elements without order.
• Maps — key-value pairs.

In Android and Java, collections are widely used for storing data, such as a list of users, a set of unique IDs, or a display of settings.

Example in Kotlin:

val users = listOf("Alice", "Bob", "Charlie")
for (user in users) {
    println(user)
}