Q: what happens to all my photos on iphoto if my mac brakes?

If a problem occurs with something other than the hard drive, they’ll remain, but you’ll need to use Target Disk mode or put it in an enclosure to retrieve the library.

If a problem occurs with the hard drive itself, it’ll take data recovery software or a professional service to retrieve them.

Back up your data.

(143705)

Nothing is saved anywhere unless you save it there

The iCloud Photo Library is not a back up, it's a sharing mechanism.

Back up your important data to an external hard disk (or two, or three).

Most Simple Back Up:

Drag the iPhoto Library from your Pictures Folder to another Disk. This will make a copy on that disk.

Slightly more complex: Use an app that will do incremental back ups. This is a very good way to work. The first time you run the back up the app will make a complete copy of the Library. Thereafter it will update the back up with the changes you have made. That makes subsequent back ups much faster. Many of these apps also have scheduling capabilities: So set it up and it will do the back up automatically.

Example of such apps: Chronosync - but there are many others. Search on MacUpdate or the App Store

Get an external drive and then use Time Machine or see the last part of Terence’s post.

(143706)

if my mac were to brake all my photos are on iphoto would they be destroyed or are they saves on icloud somewhere or??

iPhoto does not backup anything in iCloud. It can use My Photo Steam to transfer photos between devices or Shared Albums to stream selected photos to friends and family, but only mobile devices, like iPhones and iPads, can backup data in iCloud.

The newer Photos for Mac on that comes with Yosemite and El Capitan can store your Photos Library in iCloud, if yousign up for enough iCloud Storage, but then the copy in iCloud would be your only copy of the library, unless you make regular backups.

Set up Time Machine for your Mac and purchase a backup drive.See:   Use Time Machine to back up or restore your Mac - Apple Support

Buy it, hook it up to your computer, and then either accept the prompt to use it with Time Machine or use a different backup method as desired. In any case, the volume used to store an iPhoto, Aperture, or Photos library needs to be formatted as Mac OS Extended; Time Machine will reformat the drive prior to the first backup if it needs to.

(143707)

Try one of these:  OWC Mercury Elite Pro USB 3.0 / FireWire 800.  Get one that is about 3 times the size of the hard drive you'll be backing up.