iPhoto is a software application designed by Apple for importing, editing and sharing digital images.http://www.apple.com/ilife/iphoto/  It was developed in 2002, and is a part of the standard iLife software bundle which accompanies MacIntosh computers.http://www.apple.com/ilife/iphoto/ The iLife software suite also includes iMovie, iDVD, iWeb, iTunes and GarageBand software.http://8help.osu.edu/3002.html

Digital photo enhancement can adjust many issues that may have occurred at the moment of photo-taking, such as improper lighting, poor contrast, or badly framed images.http://books.google.ca/books?id=weUw89p39xEC&pg=PA45&dq=digital+photo+enhancement+why&hl=en&ei=1yRLTbHNKoL6sAPNmMyvCg&sa=X&oi=book_result&ct=result&resnum=2&ved=0CC0Q6AEwAQ#v=onepage&q=digital%20photo%20enhancement%20why&f=false  Cropping photos, straightening images, removing red-eye and improving the contrast of pictures are important adjustments to make if you are using the pictures in a digital scrapbook, sharing with your friends, or printing for framing and other uses.http://books.google.ca/books?id=weUw89p39xEC&pg=PA45&dq=digital+photo+enhancement+why&hl=en&ei=1yRLTbHNKoL6sAPNmMyvCg&sa=X&oi=book_result&ct=result&resnum=2&ved=0CC0Q6AEwAQ#v=onepage&q=digital%20photo%20enhancement%20why&f=false  With iPhoto, these corrections can be made automatically from a home computer, by those with little or no experience in photo editing.http://www.youtube.com/watch?v=v9-9GTMJqfo&feature=player_embedded  

Open iPhoto, and choose "Events" from the menu on the left sidebar of the application window.  Once you have selected an event, choose a photo to edit, and right click on the photo thumbnail. This will bring up a pop-up menu.  Choose "Edit," which will bring up the photo in the photo editor portion of the application.

Click the "Enhance" button which appears beneath the display of the photo in the editor.  This will automatically adjust settings such as color saturation and exposure. Click "Adjust" to view what corrections have been applied to the photo. Use the additional buttons on the bottom menu to crop the photograph or rotate it if needed, and to remove red-eye from the picture.  

From the "Adjust" menu, use the slider bars on the pop-up menu to make any additional enhancements you desire. Any changes you make will immediately be applied to the photograph, which is in view in the editor. Use the apple + z buttons or click "Edit" and "Undo" from the top menu to undo any changes that have been made and revert the photo to it's original state.