iPhoto provides a variety of ways to share your photos with others:
Use My Photo Stream, an iCloud feature, to keep your photos up to date on all your devices without having to sync. See My Photo Stream overview.
Use iCloud Photo Sharing to share photos, video clips, and comments about them with your friends. See iCloud Photo Sharing overview.
Email photos directly from iPhoto. See Email your photos.
Quickly create professional-quality slideshows to present to friends and family. See Create a slideshow.
Send photos to Flickr and Facebook from within iPhoto, or share photos via Messages or a Twitter account. See Ways to publish your photos on the web.
Archive or distribute photos on CDs or DVDs using OS X disc-burning procedures. See Create your own photo CDs and DVDs.
View your photos or slideshows on your iPod, iPhone, or iPad, or on your home theater system using Apple TV. See View photos or slideshows on iPod, iPhone, iPad, or Apple TV.
Export your photos in different sizes and formats to use in other applications or to send to others. See Export a photo.