* Intel or AMD's x86\_64 architecture. This is sometimes also called "x64" or "amd64" or "IA-64" or sometimes just "64-bit".
* ARM or some other architecture. These are generally lower-powered machines, like iPads. Some of the software we're proposing *might* in principle be capable of running on such machines, but installers don't seem to be available. We'll assume you have access to an x86 or x86\_64 machine.
-In the Linux example above, I could tell my machine is running x86 because the result of the `uname` command said "i386" at the end. Another machine I have says "x86\_64" at the end. On a Mac, you can also say `uname -m` in a Terminal session, and it will say something like "i386". I think that Mac OS's from Lion / 10.7 forward have all been x86\_64-only. On Windows, I don't know how to collect this information. But generally, machines running Windows XP will probably be i386/32-bit (unless it's a version of Windows with "64-bit" or "x64" in its title); machines running Windows Vista or Windows 7 or Windows 8 could be running either x86/32-bit or x64/64-bit.
+In the Linux example above, I could tell my machine is running x86 because the
+result of the `uname` command said "i386" at the end. Another machine I have
+says "x86\_64" at the end. On a Mac, you can also say `uname -m` in a Terminal
+session, and it will say something like "i386". I think that Mac OS's from Lion
+/ 10.7 forward have all been x86\_64-only. On Windows, I don't know how to
+collect this information. But generally, machines running Windows XP will
+probably be i386/32-bit (unless it's a version of Windows with "64-bit" or
+"x64" in its title); machines running Windows Vista or Windows 7 or Windows 8
+could be running either x86/32-bit or x64/64-bit.
+(Update: I found
+[this Microsoft page](http://windows.microsoft.com/en-us/windows/32-bit-and-64-bit-windows)
+that may help.)
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