Publisher Summary This chapter presents the general cultural concepts related to fungal culture media. Agar is made in many countries, some of which are self-supporting in production or are nearly so. The type of seaweed from which agar is produced is different in every country. Agars of different origin differ considerably in chemical composition and also to a greater or lesser extent in gelling capacity, melting point, hardness (percentage needed for a certain set), and viscosity. The differences depend on the type of seaweed used. Most countries use mixtures comprised of proportions of different species, the time of harvesting (condition of the weed), and the weather conditions of each individual year on which the growth of the weed will depend. Differences also arise in processing, which entail cleaning, weather bleaching, pounding, boiling, blending, acidification during boiling, addition of previous boilings, chemical bleaching, straining, setting, alternate freezing and thawing, and drying. The selection of a satisfactory medium for stimulating growth and sporulation of a particular fungus can only be found by test. A few general principles that may guide ones choice are also presented.