Many people opt to use Column View when using a Mac these days. That has been a part of OS X from early on and it seems to be a favorite for many folks. However, in Column View, the names of files and folders are often shortened and become difficult to read.
In versions of OS X, it is easy enough to click on the "handle" (the two small bars) at the bottom of the scroll bar in a Finder window and dragging the column wider so you can read the file. You could double-click on the handle and the column would automatically resize to fit the longest title. Or you could hold down the Option key and drag the handle to make all the columns change size at the same time.
However, as OS X has developed, more options have been incorporated for controlling the Column View.
As you can see in the photo, there are new options available. Now, if you Control-click (or right-click) on the handle, you'll get three new options. You can make the column you are clicking on move to a size that shows the longest name, make all columns resize to the longest name in each individual column, or make them all resize equally to the longest name in all the columns.