What is a dictionary in Python?
* The dictionary is the data type in Python where some specific value exists for some particular key.
* A Dictionary in Python is the unordered and changeable collection of data values that holds key-value pairs.
* While other compound data types have only value as an element, a dictionary has a key: value pair.
* A Dictionary in python is declared by enclosing a comma-separated list of key-value pairs using curly braces({}).
* Python Dictionary is classified into two elements: Keys and Values.
* Dictionaries are optimized to retrieve values when the key is known.
Properties of Dictionary Keys
There are two important points while using dictionary keys
* More than one entry per key is not allowed ( no duplicate key is allowed)
* The values in the dictionary can be of any type, while the keys must be immutable like numbers, tuples, or strings.
* Dictionary keys are case sensitive- Same key name but with the different cases are treated as different keys in Python dictionaries.
Dictionaries and lists share the following characteristics:
* Both are mutable.
* Both are dynamic. They can grow and shrink as needed.
* Both can be nested. A list can contain another list. A dictionary can contain another dictionary. A dictionary can also contain a list, and vice versa.
Dictionaries differ from lists primarily in how elements are accessed:
* List elements are accessed by their position in the list, via indexing.
* Dictionary elements are accessed via keys.
