Think of a list of contacts on a phone. We can search by name to find the associated phone number. In programming, we often need to connect one data piece with another. This association is what maps are perfect for!

A map is an unordered collection of keys and values. Here is an example of connecting a key of type string with a value of type int:

We are able to access map values by looking them up with a key. Unlike an array, values in a map are not accessed by indices. Maps allow for very fast lookups by organizing the values for retrieval.

We use maps for tasks such as:

• Counting the number of times unique names appear in a list.
• Mapping simple identifiers, such as an employee id, to related values.
• Anytime we need to associate any piece of data with another!

Throughout this lesson, we will introduce:

• Creating maps
• Accessing map values
• Adding and modifying values
• Removing key-value pairs

To begin using maps, we will first have to create them. We will get started in the next exercise!