I recently came across the concept of cross-validation and how one dataset is split into a few pieces and each of these pieces is then trained and tested accordingly in a repetitive manner. My friend recently told me that there are also different types of cross-validation and that they recently went through this concept in an article somewhere but couldn’t find it and neither can I find any proper article regarding it, can anyone let me know what are these types and how do they work? Even if you don’t know about all, just please mention any one type that you’re familiar with, this discussion will then have a collection of types of cross-validation for each and every one of us.