[OpenLayers-Users] How to understand and use zoom levels?

[Zhanna Maher]

Hello all,

Please excuse my simple questions; I am new to Openlayers, and 
Javascript and GIS in general.

I am wondering if anyone can offer me a source for information on zoom 
levels, scales, and resolution, or possibly some more examples of using 
the zoom bar in a functioning Openlayers project.  I think I have 
understood some of the basics of Openlayers through exploring the 
examples on the site, but I don't understand how to use these concepts. 
  The map layers I'm interested in using in my project are the topos and 
aerial photos from Terraservice, as well as Yahoo street maps.

Thanks,
Zhanna