Photography Equipment/DSLR Bodies

The body of a DSLR is the heart of the system, in the sense that it is the primary interface and that one generally has a single body (sometimes two), but many lenses. This is not to say that the body (or the sensor) is more important than the lens (indeed, the opposite in the case), but simply less variable.

Canon and Nikon
Both brands segment their line by price/target audience, and replace models on an approximately 2 year cycle. The entry-level DSLRs are the biggest sellers by a large margin.

The current ranges are: Notice that Canon model numbers are of the form "40D", while Nikon model numbers are of the form "D40".

For history, see table of Canon DSLRs and table of Nikon DSLRs, and glosses at Canon EOS DSLRs, Canon EOS model naming scheme and list of Nikon DSLRs.