Describe a dictionary in Python.

A dictionary in Python is a fundamental data structure that represents a collection of key-value pairs. This means that each item in the dictionary consists of a unique key that maps to a corresponding value. You can think of a dictionary as an unordered collection where you can efficiently retrieve, modify, or delete values based on their associated keys.

For example, if you have a dictionary that stores information about a person, you might have keys such as "name," "age," and "city," with values associated with these keys. This allows for concise and organized data management. The key serves as an index that allows for quick access to the value, making dictionaries particularly useful for storing structured data.

By contrast, the other options do not capture the essence of what a dictionary is. A list of names would refer to a simple list rather than a key-value structure. A data structure for numbers only would suggest limitations that do not apply to dictionaries, which can store values of any data type. Finally, a method for error handling does not relate to the core function of dictionaries in Python. Hence, the definition as a collection of key-value pairs encapsulates the functionality and use of dictionaries accurately.