Page 368 - Beginning Programming with Pyth - John Paul Mueller

To find a location using a relative path, you commonly use the current directory as the starting point. For example, BPPD\__pycache__ would be the relative path to the Python cache. Note that it has no drive letter or beginning backslash. However, sometimes you must add to the starting point in specific ways to define a relative path. Most platforms define these special relative path character sets:
\: The root directory of the current drive. The drive is relative, but the path begins at the root, the uppermost part, of that drive.
.\: The current directory. You use this shorthand for the current directory when the current directory name isn't known. For example, you could also define the location of the Python cache as .\__pycache__.
..\: The parent directory. You use this shorthand when the parent directory name isn't known.
..\..\: The parent of the parent directory. You can proceed up the hierarchy of directories as far as necessary to locate a particular starting point before you drill back down the hierarchy to a new location.
Creating Content for Permanent Storage
A file can contain structured or unstructured data. An example of structured data is a database in which each record has specific information in it. An employee database would include columns for name, address, employee ID, and so on. Each record would be an individual employee and each employee record would contain the name, address, and employee ID fields. An example of unstructured data is a word processing file whose text can contain any content in any order. There is no required order for the content of a paragraph, and sentences can contain any number of words. However, in both cases, the application must know how to perform CRUD operations with the file. This means that the content must be prepared in such a manner that the application can both write to and read from the file.