When should you use a key-value data structure for storing information?

The key-value data structure (for example, Dictionary in C#) should be used when you need quick access to data by a unique key. It is convenient if:

• You need to store and quickly search for elements by a unique identifier.
• The data does not require ordering, and access speed is important.
• The volume of data allows for efficient use of a hash table or a similar structure.

Example of using Dictionary in C#:

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

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

Thus, the key-value structure is suitable for caching, indexing, and quick searching.