The field of topography is a branch of geography that studies the natural and manmade features of terrain. Topographic maps take all of the details that make up a three-dimensional landscape and represent them on a flat, two-dimensional piece of paper or a three-dimensional raised relief map.
Here are some videos about topographic maps on YouTube:
Here are a couple of online tutorials about topographic maps:
Bowling Green State University (an interactive tutorial)
Geospatial Training and Analysis Cooperative (includes field exercises)
Topo Map Reading Tips for Hikers (simple tips for beginners)
Gallery of Virtual Topography (great examples of 3D topo maps!)
Topographic Map Symbol Key (downloadable PDF from the USGS)