The content available through the ArcGIS Online website is typically available at no cost for your personal or noncommercial use. As a content owner or publisher, you determine how an item can or cannot be used. This may include special restrictions, disclaimers, terms and conditions, or limitations on using the content. You might also specifically define what attribution is required when reusing the content. Before using an item you find in the website, be sure to review any special terms of use shown on the item page. For example, there might be a use constraint for a map layer that requires you to display copyright information on any screen capture that includes the layer.
If an item description does not contain information about terms of use, you can assume there are no special restrictions or limitations on using the content. If you are publishing an item based on somebody else's work, such as publishing a map that contains several layers you discovered in the website, you should adhere to and pass along any terms of use for those layers.
One option for describing your content's terms of use and simplifying use by others is to use a predefined license from Creative Commons, a nonprofit organization that standardizes ways to grant copyright permissions to creative work. Choose the Creative Commons license that matches the rights you want to reserve with your content and reference the license type on your item page.