There are three distinct privacy settings users can choose on the Info and Settings page (see Image 1) after uploading a video to YouTube: public, private, and unlisted. The characteristic of each are outlined below. Read more at YouTube's help page.
When you upload a video, by default it’s set as a “Public” video, which means that anybody can search for it and view it. The video will appear on your channel.
A private video can only be seen by you and the users you select. The video won’t appear on your channel or search results and will be invisible to other users. You need to link your channel with Google+ in order to share a private video with other users.
Making a video unlisted means that anyone who has the link to the video can view it. Your unlisted videos won’t appear to others who visit the Videos tab of your channel page. Your unlisted videos shouldn't show up in YouTube's search results unless someone adds your unlisted video to a public playlist. Anyone with the link can also re-share it in a number of ways, such as simply forwarding the link. If you don't want to allow others to re-share your video, make it Private.
To share an unlisted video, just share the link with the people who you’d like to have access to it, and they’ll be able to see it. Unlike private videos, the people you share the video with do not need a Google account to see the video. Your YouTube account needs to be in good standing to be able to create unlisted videos.