The file structure is standardised, the document you want for all the details is called the FHS (Filesystem Hierarchy Standard), though for a blog article you can also look at https://www.howtogeek.com/117435/htg-explains-the-linux-dire... for example.

For UNIX ideology (more commonly known as UNIX philosophy) you could do worse than http://www.catb.org/~esr/writings/taoup/html/index.html - especially chapter 1 for starters.

Something I learned the other day is that on Linux you can type `man hier` in a terminal to get a description of the filesystem hierarchy