High resolution pictures, videos and folders of pictures are usually much to large to send via email. A typical attachment limit is 10MB, but sending something that large can A) stall someone's mail program while downloading B) exceed Inbox quotas so people can't receive more email.
A free web service for transferring large files is filedropper.com. Simply upload your file to Filedropper and send the recipient the resulting download link. Files stay on Filedropper until they have been "idle" (no downloads) for 20 days.
The "trick" to sending multiple files is to put them into a folder and compress (zip) the folder. Right-click on the folder (or ctrl-click on Mac) and choose "Compress" or "Zip" to make the folder into one file that can be transferred.
Another free service that allows you to synchronize files between two or more computers is DropBox.com. DropBox requires software to be installed, but provides you with up to 2GB of online storage for free.