i see these terms coming up often
Though i know SATA, i dont know about other two
Could others please throw some light on it
What are these, their differences, pros and cons
This would also help other ignorant souls like me 
PATA - parallel ATA. AT Attachment - Wikipedia, the free encyclopedia
SATA - Serial ATA
Serial ATA - Wikipedia, the free encyclopedia
Wiki is your friend 
As is sTALKEr 
Advanced Technology Attachment (ATA) is a standard interface for connecting storage devices such as hard disks, solid state disks and CD-ROM drives inside personal computers.
PATA
the original ATA was retroactively renamed Parallel ATA (PATA).
IDE Drives are referred to as PATA after SATA was introduced to the market.
SATA,
Serial Advanced Technology Attachment is a computer bus primarily designed for transfer of data between a computer and mass storage devices such as hard disk drives and optical drives.
http://upload.wikimedia.org/wikipedia/commons/thumb/2/29/SATA_ports.jpg/200px-SATA_ports.jpg
eSATA,
The name suggests it… External Sata.
http://upload.wikimedia.org/wikipedia/commons/thumb/4/47/Sky_HD_Box.jpg/180px-Sky_HD_Box.jpg
Only drawback of eSATA compared to USB and Firewire is that it can not provide power. You need an external source of power for it.
At the device level, SATA and PATA devices are completely incompatible—they cannot be interconnected. At the application level, SATA devices are specified to look and act like PATA devices. In early motherboard implementations of SATA, backward compatibility allowed SATA drives to be used as drop-in replacements for PATA drives, even without native (driver-level) support at the operating system level.
EDIT: stalker beat me to it! 
the new eSATA standard is expected to make the cable carry power too.
They should’ve done it with the 1st e-SATA std itself. e-SATA is not the big success many people tout it to be.
e-SATA with power is really reqd with new HDDs crossing 1TB and necessitating a quick and easy to use interface for data transfer.
wow…thats brilliant 
Thanks guys for the time you took to explain this…much appreciated
eSata does not offer anything over SATA in terms of storage.
The advantages i thought was longer cable lengths and possibly faster transfer speeds.
Otherwise what else is there ?
It’s an extension of the SATA interface to connect HDDs externally. It won’t offer anything better v/s SATA but against USB, it can offer a high rate of data transfer…good when you are filling up a HDD or transferring some movies.
Anyone who has tried filling 500GB using USB will be able to relate. It takes hours to complete the task.
There is one more difference i forgot to mention, and found out when researching enclosures…
eSata allows the OS to control spin down of the HD whereas USB won’t. If the drive does spindown and it has a USB interface then its more likely that the firmware for the enclosure allows it.
granted this is more of a esata vs USB..but bear with me anyway…
So for external storage and if it’s running 24/7, that little factor can nearly dbl the lifetime of the drive being used. Allows you to set spindown after say x hours of inactivity.
less spin = less wear & tear etc etc.
Now if you don’t run your external 24/7 none of the above applies.