We examined the use of the append and extend commands in Python. We learned that these commands modify a list that is in place but do not return a new list. Then we learned how to use negative indexing in an array to access items from the end of the array. The need to access the last log entry or last user input is common when writing programs. Without the use of a negative index, you would have to calculate the end of an array making your program more verbose. We discovered that negative indexing is cleaner and easier making the Python code more readable and concise.