Pre-service training course
A pre-service training course is a teacher training course aimed at those with little or no experience of teaching.
The two with the most recognition and are CELTA (Cambridge) and CertTESOL (Trinity). They both take about a month to complete, and the experience is pretty intensive. Both of these are certified, which means that they have quality control.
However, there are also a variety of other courses, which may or may not be certified, that are available.