The nucleosome is the fundamental structural unit of chromosome fibers. A DNA wraps around a histone octamer to form a nucleosome, while neighboring nucleosomes interact to form higher-order structures and fit gigabase-long DNAs into a small volume of the nucleus. Nucleosomes interrupt the access of transcription factors to a genomic region, and provide regulatory controls of gene expression. Biochemical and physical cues stimulate wrapping–unwrapping and condensation–decondensation dynamics of nucleosomes and nucleosome arrays. Changing the ionic background in the nucleus modulates these dynamics in various ways, chemically altering the histone proteins through post-translational modifications, or controlling the sequence context of the histone-binding DNA motifs. Biochemical and biophysical measurements, along with in silico simulations, have been extensively used to study the regulatory effects on chromatin dynamics. In particular, single-molecule measurements have revealed novel mechanistic details of nucleosome and chromatin dynamics. This minireview elucidates recent findings on chromatin dynamics from these approaches.