layer object vs. layer name

GeorgeRiner

I don't understand when an input argument to an arcpy function that says it takes a layer as an input but it really only works when I give it the name of the layer. Specifically: I use the arcpy.mapping.ListLayers() function to get a list of all the 'layers' in my mxd. I then search through this list to find the layer for which the .name value of the layer I'm interested in. I then copy this layer object out of the list returned by ListLayers(). I assume that what I have is a layer in the sense of what's documented