Block Visibility by Term extends the block visibility interface in Drupal 7 and allows the user to control block visibility based on the terms that a node is tagged with. For each block, taxonomy terms can be selected. If the displayed node is tagged with at least one of those terms, the block will be visible; if not, it will be hidden.
A popular and excellent alternative to this module is Context. A Drupal 8 version of this module is not anticipated.