If you regularly use the OS X Finder to manage your files, then you may find yourself organizing them in a classic fashion by first creating folders and then dragging items into these folders. While the final result is a classic hierarchy structure, the two-step process of creating a folder and then dragging items into it can be mundane, especially if you are organizing many files into different folders.
To help with this, OS X supports a quicker way to create a new folder containing files. Simply select your files, then right-click the selection and choose "New Folder with Selection (# items)," or you can press Control-Command-N to perform the same action.
When you do this, the selected items will be consolidated into a new folder whose name will be editable so you can change it from the default "New Folder With Items" to whatever you want.
This feature may seem like a small augmentation to creating a folder, but it can be used quite nicely to create a hierarchy of files, provided they are located in the same folder to begin with.
For example, if you have a number of text files and JPEG images on your desktop, you can form a hierarchy of them by selecting them all (minus your hard drives) and then pressing Control-Command-N to encase them all in a new folder. Next, open this folder and perform the same action with a subset of files, such as all of the images. This will then place the image selections in a new subfolder; you can continue to do the same for specific image contents or other criteria within this folder.
This approach can be done in reverse as well, where you can initially select the images on your desktop and create a folder to contain them, then select the folder along with the text files and press Control-Command-N to create a new directory including all of them. You can also select the text files and encase them in a folder, then select both the images and text folder to encase both folders in a parent folder.