In Go, global variables are defined at the package level and can be accessed from anywhere within the package, whereas local variables are defined within a function or a block and can only be accessed from within that function or block.
Global variables are typically used for storing configuration settings or shared state that needs to be accessed by multiple functions within a package. They are initialized when the package is loaded and their values persist for the lifetime of the program.
Local variables, on the other hand, are used for temporary storage within a function or a block. They are typically initialized when the function is called and their values are discarded when the function returns.
One important consideration when using global variables is to ensure that they are accessed safely from concurrent goroutines, as concurrent access to shared state can lead to race conditions and other bugs. It's often recommended to use channels or other synchronization primitives to coordinate access to shared state between goroutines.