What collection object types are suitable for iteration using a foreach loop?

In C#, the foreach construct is used with collections that implement the IEnumerable or IEnumerable<T> interface. This means you can iterate over:

• Arrays (e.g., int[], string[])
• Lists (List<T>)
• Sets (HashSet<T>)
• Dictionaries (Dictionary<TKey, TValue>) — iterating over key-value pairs
• Any other collections that implement IEnumerable

Example:

List<string> names = new List<string> { "Anna", "Boris", "Victor" };
foreach (var name in names)
{
    Console.WriteLine(name);
}

Thus, foreach is convenient for iterating over any collections that support enumeration.