In Python, lists are a versatile datatype that can contain multiple different data types within the same square brackets. The data types include numbers, strings, other objects, and even other lists.

Lists are defined using square brackets [ ] containing a comma separated list of values.

In Python, datatypes that can be iterated (called iterables) can be used with the zip() function to aggregate data based on the iterables passed in. As shown in the example above, zip() is aggregating the data between the owners’ names and the dogs’ names to match the owner to their dogs. zip() returns an iterator containing the data based on what the user passes through and can be printed to visually represent the aggregated data. Empty iterables passed in will result in an empty iterator.

In Python, you can add values to the end of a list using the .append() method. This will place the object passed in as a new element at the very end of the list. Printing the list afterwards will visually show the appended value. This .append() method is NOT to be confused with returning an entirely new list with the passed object.

In Python, lists can be added to each other using the plus symbol (+). As shown in the code block, this will result in a new list containing the same items in the same order with the first list’s items coming first. An important thing to remember is that this will not work for adding one item at a time (use .append() method). In order to add one item, create a new list with a single value and then use to plus symbol to add the list.

The Python len() function can be used to determine the number of items found in the list it accepts as an argument.

An item’s position in a list is represented by its index. In Python, list indexing begins at zero, and ends at the length of the list minus one. For example, in this list, 'Andy' is found at index 2.

Python list elements are ordered by index, a number referring to their placement in the list. List indices start at 0 and increment by one.

Indices can also be used as negative numbers, referring to the placement from the end of a list. The last element of a list is index -1, the second-to-last is -2 and so on.

To access a list element by index, square bracket notation is used: list[index].

A slice, or sub-list of Python list elements can be selected from a list using a colon-separated starting and ending point.

The syntax pattern is myList[START_NUMBER:END_NUMBER]. The slice will include the START_NUMBER index, and everything until but excluding the END_NUMBER item.

When slicing a list, a new list is returned, so if the slice is saved and then altered, the original list remains the same.

In Python, when selecting a range of list items, if the first item to be selected is at index 0, no index needs to be specified before the :. Similarly, if the last item selected is the last item in the list, no index needs to be specified after the :.

Negative indices for lists in Python can be used to reference elements in relation to the end of a list. This can be used to access single list elements or as part of defining a list range.

For instance, the last element of a list is accessed with my_list[-1].

To select the last three elements: my_list[-3:]. To select everything except the last two elements: my_list[:-2].

The .count() Python list method searches a list for whatever search term it receives as an argument, then returns the number of matching entries found.

The .sort() Python list method will sort the contents of whatever list it is called on. Numerical lists will be sorted in ascending order, and lists of Strings will be sorted into alphabetical order. It modifies the original list, and has no return value.

The Python sorted() function accepts a list as an argument, and will return a new, sorted list containing the same elements as the original. Numerical lists will be sorted in ascending order, and lists of Strings will be sorted into alphabetical order. It does not modify the original, unsorted list.