It is the logical unit of execution that contains the actual instructions for our program/functions to run. It also contains other important information regarding the goroutine, such as the stack memory, which machine (M) it is running on, and which Go function called it. The following are some of the elements in the goroutine struct that might come in handy for this section:

// Denoted as G in runtime 
type g struct { 
    stack         stack // offset known to runtime/cgo 
    m               *m    // current m; offset known to arm liblink 
    goid           int64 
    waitsince   int64   // approx time when the g become blocked 
    waitreason string  // if status==Gwaiting 
    gopc          uintptr // pc of go statement that created this goroutine 
    startpc       uintptr // pc of goroutine function 
    timer         *timer  // cached timer for time.Sleep 
 
    // ... 
} 

An interesting thing to know is that when our Go program starts, a goroutine called main goroutine is first launched, and it takes care of setting up the runtime space before starting our program. A typical runtime setup might include things such as maximum stack size, enabling garbage collector, and so on.