The Finder in OS X has four views: Icon, List, Cover Flow, and Column, which can be activated on any Finder window to display its contents in different ways.
Each has its perks and uses, though many may often use column view because it shows multiple levels of a directory tree in the same window and can therefore help in organizing and navigating files.
While this feature makes navigating and moving files around a bit easier, often when you scroll up or down in column view the column size will not change. This sometimes results in long file names being truncated or the column being too wide and taking up window space.
To get around these drawbacks of the column view, Apple provides some options for resizing the columns:
The basic option for resizing columns in OS X is to click and drag the column separator (to the right of the column), which will expand or shrink it accordingly; however, this can be a bit of a burden if you need to expand multiple columns in a window. In addition to dragging one column, you can dynamically set all the columns to the same size by holding the Option key when dragging one column separator.
- Contextual menu options
If you right-click the column separator, you will see a contextual menu appear that contains three additional options for "Right-sizing" the column, which pertain to the current column, all columns equally, and all columns individually. These options will automatically adjust the columns to resize to the current content, all contents, or set them to be equal in size.
The functions provided in the contextual menu can also be invoked by double-clicking the column with or without providing modifier key inputs. If you directly double-click the column separator then its column will be resized to fit its contents, but if you hold the Option key while doing this then all the columns in the window will be resized to fit their contents. Alternatively, if you hold both the Shift and Option keys when double-clicking, then all of the columns will be set to the same size.
These options in OS X provide you with the functions that Apple offers for adjusting column sizes. Unfortunately this means that there is no way to have columns automatically resize to fit their contents--a convenience that Apple has somehow skirted through the various OS X iterations. There does not seem to be a reason why Apple would avoid such an option, so hopefully it will make its way into the OS in a future version. For now, however, you will need to use one of these manual adjustment to resize columns in the Finder.