Kefir is a fermented dairy beverage produced using the natural microbiota of kefir grains or freeze-dried starter cultures. These grains are composed of a symbiotic community of microorganisms, including Kluyveromyces marxianus, Saccharomyces unisporus, Saccharomyces cerevisiae, Saccharomyces exiguus, as well as different strains of the genera Lactobacillus, Leuconostoc, Lactococcus, and Acetobacter. When fermented, these microorganisms transform milk into a probiotic beverage rich in nutrients and bioactive compounds, promoting health benefits. There are several methods for kefir production, with the traditional and industrial methods being the most commonly used. The traditional method, widely employed by small producers, involves inoculating milk with kefir grains. On the other hand, the industrial method, used by large manufacturers, aims for reproducibility and quality control on a large scale, using freeze-dried kefir cultures added directly to the milk. Given the importance and popularity of both methods, this chapter provides a detailed description of the two main methods of milk kefir production: traditional and industrial. Each approach’s key technical and practical aspects will be explored, providing a comprehensive guide for small artisanal producers and large-scale industrial operations.