What types of data structures do you use in your work?

In working with C#, I often use the following data structures:

• Arrays (Array) — for storing a fixed number of elements of the same type.
• Lists (List<T>) — dynamic collections, convenient for adding and removing elements.
• Dictionaries (Dictionary<TKey, TValue>) — for quick access to data by key.
• Queues (Queue<T>) and Stacks (Stack<T>) — for organizing data in FIFO and LIFO order respectively.
• HashSet<T> — for storing unique elements.

For example, to store and quickly search for users by ID, it is convenient to use a Dictionary:

var users = new Dictionary<int, string>();
users.Add(1, "Ivan");
users.Add(2, "Maria");

string userName = users[1]; // "Ivan"