iPhoto ’09 organizes the photos in your photo library by Event. An Event groups photos taken in a certain period of time, such as photos shot during an afternoon wedding or a Saturday beach outing.

When you view all your Events in the iPhoto window, one photo is visible at a time, but you can move your pointer over, or “skim,” each Event, revealing all the pictures in succession.

You can choose one photo per Event to appear as the “key photo” when you view Events. You can also “expand” Events to see all the photos in one Event, or to show all photos in all Events.

You can choose to move photos from one Event to another, merge or split Events, or rename an Event. You can still add keywords or ratings to particular photos. And you can use Events or selected photos to create albums, slideshows, books, calendars, and cards. You can also publish your photo albums to your MobileMe Gallery, Facebook, or Flickr.

Although Events are similar to “film rolls” (the organization used in previous versions of iPhoto), Events provide easier access to your photos. When you upgrade from iPhoto 6 or earlier, iPhoto converts all your film rolls into Events.

During importing, photos can be grouped into one Event or several, depending on your preference. If you choose to split the photos in your camera into several Events, iPhoto creates those Events by grouping the photos by the date they were taken.