hardware/mobo+case question

what size motherboard fits into a mid-size case? ATX or Micro ATX? and what is a mini ITX good for. im building a new pc and i want a mid tower. my last was a full tower and it is huge, looks cool but to big.
Answer #1
Micro ATX fits into a mid-size case and mini ITX systems are extra small and often used for Car PC systems, or Carputers. No doubt they have many other uses too, wherever size is needed to be kept to a minimum.
Answer #2
is there any downfalls to using a MicroATX? should i use a regular ATX instead? maybe a microATX doesnt have all the features as a regular ATX? will a regular ATX even fit into a mid tower case? thanks for your help.
Answer #3
MicroATX might not have as many slots (RAM, AGP, PCI/PCI-E, whatever) as a standard ATX.
Sometimes you can get away with putting a smaller board into a bigger case, but sometimes the screw-holes won’t line up.
Answer #4
ok, thanks both you guys.
Answer #5
the case should say what mobo it take in the spec
I think
full size – ATX (12.0″ x 9.6″)
mid size – ATX
small – Micro ATX (9.6″ x 9.6″)
Dimension                  microATX board           ATX board, full-sized
Maximum width allowable   9.6 inches (244 mm)      12 inches (305mm)
Maximum depth allowable   9.6 inches (244 mm)     9.6 inches (244mm)

Answer #6
The micro-atx motherboards usually lack features compared to the regular atx versions. Also, if you are overclocking, avoid micro-atx. Unless you have a micro-atx case, there is really no reason to buy a mico-atx board.