The latest measurements obtained by the CMS Collaboration in single top quark production are summarized. We present both inclusive and differential cross section measurements in different production modes, which lead to constraints on proton parton distribution functions (PDFs) and measurements of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $|\textrm{V}_{\textrm{tb}}|$ and top quark spin asymmetry $\text{A}_{\ell}$; we also show searches for rare Standard Model (SM) processes, such as the first observation of tZq associated production and the first evidence for t$\gamma$q associated production.