XMP files

I recently installed photoshop CS 5 on my computer.I bought a new computer, CS 5, and lightroom 4 about a year ago but just recently set up the computer with photoshop. I still haven't loaded Lightroom 4 onto the computer. I have been using Nikon View NX2 for my RAW file conversions and a very old version of Photoshop and I have been content with how they worked but when I got the new computer I finally decided to update my software. I have been familiarizing myself with the new version of photoshop and I noticed that everytime I open a RAW file in ACR it creates an XMP file in the original folder. What is this file for? When I click on the file to open it nothing happens. Is this file really necessary? Can I just delete it? Should I delete it.

The only thing I am really interested in is maintaining the complete original NEF (RAW) file for my permanent files. Any other files that complicate matters for me, take up space on my drive etc. aren't really of interest to me but I don't want to dump any files that may be important down the road.

Please keep the language simple and not to much technical jargon because I am really not to hot with computers. Respond like you are talking to a dim bulb (I'm usually not a dim bulb but I definitely ain't to bright when it comes to computers.)

I also need info on DNG files but I'll put that in a later post.

Thanks for any help you can offer.

XMP files, commonly called sidecar files, are where the RAW processing instructions are stored when you perform raw processing in Adobe Camera Raw. You do not want to delete the XMP files unless you would like to recreate the RAW processing that you've done on an image.

You can see what's in the EXIF and XMP and other metadata by going to File>File Info in Photo Shop.

As Keith says, you definitely want to keep the XMP sidecar files.

--P

They answered your questions correctly, but I'm just curious why you need Lightroom if you use both NikonView and PS.

Saving your edits in DNG format embeds the XMP file.
If you save your edits in your native file format, ACR creates the XMP file to carry instructions, as mentioned above.
Copying your file to another folder requires you to copy the associated XMP file with it, or you lose all your edits when opening in a new location.
There are advantages and disadvantages to each.
Simply, your choice.

Thanks to all for the replies to my question. I had ViewNX2 on my old computer but haven't downloaded it on my new one. When I purchased my CS 5 about a year ago I believe lightroom was on sale when purchased with PS so I picked it up also.