  We present the most recent measurements of single top quark production cross
section by the CDF and D0 experiments at the Fermilab Tevatron Collider and the
ATLAS and CMS experiments at the Large Hadron Collider (LHC). The data were
collected at the Tevatron corresponding to an integrated luminosity of up to
9.7 fb$^{-1}$ of proton-antiproton ($p\bar p$) collisions at a centre-of-mass
energy of 1.96 TeV and at the LHC corresponding to an integrated luminosity of
up to 4.9 fb$^{-1}$ of proton-proton ($pp$) collisions at a centre-of-mass
energy of 7 TeV in 2011 and up to 20.3 fb$^{-1}$ at a centre-of-mass energy of
8 TeV in 2012. The measurements of single top quark production in $s$-channel,
$t$-channel and associated production of a top quark and a $W$-boson ($tW$
production) are presented separately and lower limits on the CKM matrix element
$|V_{tb}|$ from the single top quark cross section are set.
