Synchronization implies the existence of a temporal relationship between two or more brain regions. When this relationship is anatomical, there is no doubt that the two are related. But when the relationship between them is temporal, its assessment is more difficult. Various tools have been developed to determine the existence and intensity of synchronization. These methods are divided according to their dependence on an underlying model, or their lack thereof. Both types of methods can use time- or frequency-domain data. We will briefly describe some of the most commonly used methods, without going into detail. Finally, we will discuss two of the main problems encountered in determining synchronization. These problems are, first, the existence of spurious synchronization due to the common electrode effect, which occurs in reference setups, and second, the apparent synchronization that occurs due to volume conduction. The use of differential setups and some methods that allow phase analysis can help minimize these problems.