Randomized complete block is a design with each block containing each level of a treatment factor, or combination of levels for multiple factors. The randomization of treatment levels is therefore restricted to plots within blocks. The Latin Square is a variant on this design for two blocking factors.
Doncaster, C. P. & Davey, A. J. H. (2007) Analysis of Variance and Covariance: How to Choose and Construct Models for the Life Sciences. Cambridge: Cambridge University Press.