Users may create content of various types.  Creation, in this sense, is not necessarily limited to just creating a new node.  There are actually a series of permissions reflecting what a user may, or may not, do to a node:

• Create [content type]
• Edit own [content type]
• Edit any [content type]
• Delete own [content type]
• Delete any [content type]

Generally speaking, if a user may create a given content type, he or she may also edit and/or delete that node.  Exceptions are noted on individual content type pages.

A large bit more information can now go here.  The more user-directed information has been moved to its own page.  This page (and presumably its child pages) will be reserved primarily for administrative information.

Those wanting a deeper understanding of how things work around here are also welcome to peruse this section.