Global Modules and Rows
A global element is something that is the same across your entire website. This is really useful for things that show up everywhere, but should always be the same.
For example, you may use a contact form on your website on a few different places where "contact me" is the most appropriate call to action.
If this is the case, and your email address changed, you'd want to update your contact form.
Global modules and rows always have an orange color to indicate it's "globalness".
With a global contact form module, you only need to make this update once, and you'll know that anywhere this form is on your website it will be updated as well.
There are many ways to use global elements, but once you save something as global you can't save it back... so be careful since it's a commitment.
When should you NOT use global modules or rows?
Buttons make great saved modules, but aren't so helpful if they are global except for in a few instances.
For example, if you have a new program and you want a button that says "learn more", you want to be able to change the page this button goes to. If it was global you could not make this change.
In most cases, a saved module or row is good enough.