RAID 0:
Block striping, yields higher performance than with individual drives. There is no redundancy.
ex.
disk1 = 80G
disk2 = 100G
total space = 160G

RAID 1:
Drives are paired and mirrored. All data is 100% duplicated on an
equivalent drive. Fully redundant. total space is equal to the size of the smallest disk.
ex.
disk1 = 80G
disk2 = 100G
total space = 80G

RAID 5:
Data is striped across several physical drives. Parity protection is used
for data redundancy. Parity is stored on each disk. (in RAID 3, parity is stored in single disk). supports single disk failure.
ex.
disk1 = 80G
disk2 = 100G
disk3 = 120G
total space = 80*2=160G