We characterize the notion of definable compactness for topological spaces definable
in o-minimal structures, answering questions posed by Peterzil and Steinhorn (J. LondonMath. Soc.59:3 (1999), 769–786) and Johnson (J. Symb. Log. 83:4 (2018), 1477–1500).
Specifically, we prove the equivalence of various definitions of definable compactness
in the literature, including those in terms of definable curves, definable types and
definable downward directed families of closed sets.