When you import photos using a digital camera, events are created. Where do the original photos (source photos) go? In other words once downloaded, if I format my camera will I still have the full size photo on my computer and, if so, where will they be?

Your pictures are stored in the iPhoto Library file, usually found in your user/pictures folder. IPhoto keeps two copies, the original and the edited (modified) version.

Just a bit to add to Dansyacht's post: as long as you're running a "managed" library, i.e. one where iPhoto copies the image file into the library during import, the files will be located inside the iPhoto Library:

OT

Since iPhoto 7 (iLife 08) the old iPhoto Library Folder is a Package File. This is simply a folder that looks like a file in the Finder. The change was made to the format of the iPhoto library because many users were inadvertently corrupting their library by browsing through it with other software or making changes in it themselves.

Want to see inside?

Go to your Pictures Folder and find the iPhoto Library there. Right (or Control-) Click on the icon and select 'Show Package Contents'. A finder window will open with the Library exposed.

Standard Warning: Don't change anything in the iPhoto Library Folder via the Finder or any other application. iPhoto depends on the structure as well as the contents of this folder. Moving things, renaming things,, deleting them or otherwise making changes will prevent iPhoto from working and could even cause you to damage or lose your photos.

There are many, many ways to access your files in iPhoto: You can use any Open / Attach / Browse dialogue. On the left there's a Media heading, your pics can be accessed there. Command-Click for selecting multiple pics.

(Note the above illustration is not a Finder Window. It's the dialogue you get when you go File -> Open)

You can access the Library from the New Message Window in Mail:

There's a similar option in Outlook and many, many other apps. If you use Apple's Mail, Entourage, AOL or Eudora you can email from within iPhoto.

If you use a Cocoa-based Browser such as Safari, you can drag the pics from the iPhoto Window to the Attach window in the browser.

If you want to access the files with iPhoto not running:

For users of 10.6 and later: You can download a free Services component from MacOSXAutomation which will give you access to the iPhoto Library from your Services Menu.

Using the Services Preference Pane you can even create a keyboard shortcut for it.

For Users of 10.4 and 10.5 Create a Media Browser using Automator (takes about 10 seconds) or use this free utility Karelia iMedia Browser

Other options include:

Drag and Drop: Drag a photo from the iPhoto Window to the desktop, there iPhoto will make a full-sized copy of the pic.

File -> Export: Select the files in the iPhoto Window and go File -> Export. The dialogue will give you various options, including altering the format, naming the files and changing the size. Again, producing a copy.

Show File: a. On iPhoto 09 and earlier: Right- (or Control-) Click on a pic and in the resulting dialogue choose 'Show File'. A Finder window will pop open with the file already selected. 3.b.

b: On iPhoto 11 and later: Select one of the affected photos in the iPhoto Window and go File -> Reveal in Finder -> Original. A Finder window will pop open with the file already selected.