[Term Entry] Python Built-in Function: .id()

content/python/concepts/built-in-functions/terms/id/id.md

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+---
+Title: 'id()'
+Description: 'Gives a unique number for any object in Python.'
+Subjects:
+  - 'Computer Science'
+  - 'Data Science'
+Tags:
+  - 'Functions'
+  - 'Methods'
+  - 'Id'
+  - 'Memory'
+  - 'Debugging'
+CatalogContent:
+  - 'learn-python-3'
+  - 'paths/computer-science'
+  - 'paths/data-science'
+---
+
+The **`id()`** function gives a unique number for any object in Python. This number is the location of the object in the computer’s memory. This will be consistent for the duration of the object's lifetime.
+
+## Syntax
+
+```pseudo
+id(object)
+```
+
+The parameter, `object`, can be any given object such as a string, list, number, dictionary, etc.
+
+## Example
+
+In the example below, when two **immutable** variables are compared using the `id()` function, both return the same value pointing to the same location in memory.
+
+This is because immutable objects don't change. The following example uses an immutable `string` object to demonstrate this:
+
+```py
+color = 'green'
+
+favColor = 'green'
+
+print(id(color))
+
+print(id(favColor))
+```
+
+This example results in something resembling the following output:
+
+```shell
+140307997340656
+140307997340656
+```
+
+## Example 2
+
+In this next example, the `id()` function will be executed with two **mutable** variables. Take note of how the function will return different values: two separate unique ids.
+
+This is because mutable objects are able to change. A mutable `list` object can be used to demonstrate this:
+
+```py
+animals = ['lions', 'tigers', 'bears']
+
+favAnimals = ['lions', 'tigers', 'bears']
+
+print(id(animals))
+
+print(id(favAnimals))
+```
+
+This example results in something resembling the following output:
+
+```shell
+140279020355392
+140279020204352
+```
+
+## Codebyte Example
+
+The following example displays the output of two immutable `number` objects:
+
+```codebyte/python
+hello = 30
+goodbye = 30
+
+print(id(hello))
+print(id(goodbye))
+```