Where Windows has Explorer, Mac OS has Finder. Both let you preview and manage files and launch applications, but there's some notable differences in how they work, especially if you use the keyboard for navigating. Here's the main ones to watch out for.
Lots of it is the same. On both platforms, you can navigate through lists using the arrow keys, and type individual letters to jump to files or folders starting with that letter. You can also drag files between different windows to copy or move them. (To open extra Finder windows, select File —> New Finder Window or type Command-N.)
By default, files will copy if dragged to a different drive, and move if dragged somewhere else on the same drive. To force a file to copy, hold down the Option while dragging. To force it to move, hold down Command while dragging.
There are four basic views in Finder. You can access these by clicking on the small group of buttons at the top of the window, by selecting them from the View menu, or by using the keyboard shortcuts we're mentioning here.
Icons (Command-1) shows the name. List (Command-2) displays filename, type, size and date modified. Columns (Command-3) shows a brief list; as you open folders, these display alongside the original list in additional columns. Cover Flow (Command-4) lets you scroll through the files while offering a preview of their contents. You can open most files in the built-in Preview app by tapping on Space when they are selected.
Keys won't do what you'd expect. In Windows, selecting a file and hitting Enter opens the file. On the Mac, it lets you rename the file. To open the file, double-click it or type Command-O.
While you can use Copy (Command-C) and Paste (Command-V) to make a copy of a file, you can't use Control-X to cut one and then move it elsewhere. If that bugs you (it certainly bugs me), you can fix that behaviour with an Automator script or use MoveAddict (though the latter is a paid app).
On Windows, you can hit the Backspace key to move up a directory. To get the same effect in Mac OS, type Command-Up Arrow.
To delete files in Finder, type Command-Delete — the Delete key on its own won't work. (The non-keyboard equivalent is to drag to the Trash can on the Dock.)
Folders get mixed in with other files. In standard Explorer views, folders are always listed at the top, before individual files, which makes it easy to drill down to sub-directories. On the Mac, this doesn't happen; folders are treated the same as files (and hence sorted by name in the default view). If you're used to navigating down through folders by keyboard, this slows the process quite a bit.
There doesn't seem to be a simple way to fix this. You can rename folders to all start with a space, or choose View — Arrange by — Kind to show files by type. That will put folders together at the top, but won't necessarily arrange other files in the order you want them.
File types and associations. Like Windows, by default Mac OS doesn't show file extensions. You can change this by choosing Preferences on the Finder menu (or use Command-Comma), going to the Advanced tab and ensuring that 'Show all filename extensions' is checked. It's a truly system-wide change; if you do this, all your apps will show up as .app files in your Applications window, for instance.
If you want to change the application used to launch a particular file type, select a file of the relevant type in Finder and choose 'Get Info' from the File menu (or use Command-I as a shortcut). In the Open with section, choose the application you want, and then click the Change All button under the sentence 'Use this application to open all documents like this one'.
MacBook Migrant is a week-long series of posts highlighting tricks new or aspiring Mac owners familiar with Windows can use to ease the transition.