The directory structure that all projects must follow for readability and consistency.
app directory: contains the slim controllers and the views
data directory: contains files concerning the database
html directory: contains files accessible directly to the user (anything that doesn't require protection)
notes directory: contains any updates of work or explanation
vendor directory: contains dependencies downloaded with composer (not shown in the pic)
composer.(json/lock) file: created by composer
propel.yml[.dist] file: created by propel to define a connection
README.md file: short project description
config.php file: contains the array needed for slim settings, and other functions that should be available globally
Window uses \ as a path delimiter, while Unix-based machines use /, for the following commands concerning paths (such as vendor/bin/propel init) make sure to use the path separator corresponding to your machine. Keep in mind that the directory structure is used to keep projects organized, and is subject to tweaks, but the main structure will stay relatively similar from project to project.