Executive functions are a set of supervisory processes that control lower-level operations in the service of goal oriented behavior. The most commonly accepted "core" executive functions are shifting, updating, and inhibition (Miyake, Friedman, Emerson, Witzki, & Howerter, 2000). Other terms are sometimes used interchangeably (e.g., flexibility for shifting, control for inhibition, and working memory for updating; Diamond, 2013). Executive functions are believed to be somewhat discrete, though intercorrelated. The prefrontal cortex and anterior cingulate gyrus are associated with tasks that measure executive function. Common tasks include the Tower of Hanoi and the Wisconsin Card Sort Task.
Diamond, A. (2013). Executive functions. Annual Review Of Psychology, 64135-168. doi:10.1146/annurev-psych-113011-143750
Miyake, A., Friedman, N. P., Emerson, M. J., Witzki, A. H., & Howerter, A. (2000). The unity and diversity of executive functions and their contributions to complex 'frontal lobe' tasks: A latent variable analysis. Cognitive Psychology, 41(1), 49-100. doi:10.1006/cogp.1999.0734