What types of data are suitable for use as keys in a Map structure?

In Go, the keys in a map structure can only be of types that support comparison operations for equality (== and !=). This is because, to find a value by key, the keys need to be compared.

Suitable key types:

• Basic types: int, float64, string, bool, etc.
• Pointers
• Structs, if all their fields are comparable
• Arrays, if elements are comparable

Cannot be used as keys:

• Slices (slice)
• Maps (map)
• Functions

Example usage:

m := make(map[string]int)
m["apple"] = 5
m["banana"] = 3

fmt.Println(m["apple"]) // 5

Trying to use a slice as a key will result in a compile-time error.