If there’s one thing you can count on with Apple, it’s that the next Mac you buy probably has a different display connector than the one you have now. Apple has utilized an utterly ridiculous number of different kinds of ports for attaching displays. Let’s take a look.

These are the normal ones:
DVI— common digital video standard found on many Mac laptops and towers; adaptable to HDMI*, ADC, and VGA
HDMI — common digital video+audio standard, found on the new Mac Mini only; adaptable to DVI*
VGA — common analog video standard found on older PowerBooks and desktops; adaptable to DA-15

And these are the crazy Apple ones:
Mini DisplayPort — found on all current Mac products; adaptable to DVI, HDMI*, and VGA
Mini-DVI — found on many laptops, iMacs and Mac minis; adaptable to DVI, VGA, and S-Video/composite
Micro-DVI — on first generation MacBook Air only; adaptable to DVI, VGA, and S-Video/composite
ADC — DVI, USB, and power in one connector, found on some PowerPC Mac towers; adaptable to DVI* and VGA*
Mini-VGA — iBooks and first 12″ PowerBook G4; adaptable to VGA and S-Video/composite
HDI-45 — found on first-generation Power Macintoshes only; adaptable to DB-15
DA-15 — very old desktops; adaptable to VGA*
mini-15 — very old PowerBooks; adaptable to DA-15

* adapter is made by third-party, not Apple

Note that while the various styles of built-in DVI ports can be adapted to VGA, you can’t use the DVI port on an adapter for this.

And several machines also included S-Video or composite out as well as the higher resolution outputs above . Thanks to this Wikipedia article for filling in the holes in my memory.

That is an absurd number of connectors!