What's the difference between ATA, PATA, and IDE?

IDE (Integrated Drive Electronics) was the original name, then they standardized on ATA (Advanced Technology Attachment) as being a broader standard that included additions like CD-ROMs and such. When SATA ( Serial ATA ) came out, people started using PATA (Parallel ATA) to refer to the older parallel connected bus (those using ribbon cable), to be more specific than the term ATA, which can refer to either. Both are part of the ATA standard, and use the same logical command sets, but SATA obviously has a different electrical interface. Both types of drives (SATA and PATA) are IDE devices.

Source: PC mag

I found an interesting article here that explains the difference. It appears that it was actually called ATA, but IDE and PATA were just different names used by different branding.

It just goes to show how much competition (and money) there is amongst computer related companies to have their particular brand of the current technology accepted as the world standard. However, they all dipped out as plain old 'ATA' became the accepted term.

Once SATA was developed, it was named PATA.

All in all, the ATA standard has moved through seven recognised phases, (ATA-1, 2, 3, etc) and in 2001 stage 7 ATA hard drives came on the market (commonly called Ultra ATA-133). These could make data transfer rates of up to133 MB/sec (megabytes per second). ATA-7 is thought to be the last stage of development before Serial ATA took over. At this stage to make clear the distinction between ATA and the newer SATA standard, the older ATA standard was redefined and named Parallel ATA (or PATA).

Integrated Drive Electronics was the original marketing name to differentiate from when the electronics were on a separate board (ST-506 and ESDI). But for example, SCSI drives also have their controllers integrated. So the standard was named "AT Attachment" for the IBM PC/AT (which in turn meant Advanced Technology, but ATA is not Advanced Technology Attachment). But IDE and ATA are synonymous. ATA is a better term.

ATA became PATA (Parallel) to differentiate from SATA (serial)

Every SATA drive have an on-board chip-set that compress and decompress the data transfer, where as the PATA controller, on-board the motherboard, communicated directly with the drive's hardware before.

SATA to motherboard the data is compressed, the motherboard then has it's own chip-set which turns the data from the SATA device back into decompressed binary for the rest of the computer, the same has to be done for data being passed from the motherboard to the hard-drive.

Any transfer to/from the drives has to go through this process or neither components will understand the other.