As we know, there are many methods available to connect raspberry pi module. If you don't have any keyboard or monitor. VNC viewer method is easiest way to connect raspberry pi. On the other hand, the most using way to connection method is SSH. SSH means "Secure Shell (SSH) is a cryptographic network protocol for operating network services securely over an unsecured network." and it also known as secure remote login. VNC means "It is a platform-independent architecture that allows us to use and manage graphical interface applications running on any network server easily and quickly from any other networked computer".
If you are using raspberry pi 3 , you are lucky. Because VNC setting is default open in this raspberry version. You can check the under raspi-config menu ---> interfacing options --> vnc .
After that you have to VNC Viewer program in Windows or Mac OS or Linux Distributions.
You have to detect your raspberry pi's ip address. So that you can use wifi or ethernet to connect pi. If you don't have connect any gui options (tv, monitor etc.) you cannot connect wifi area easily. (If the wifi network has password)
If raspberry is connected via LAN. It becomes online automaticly. The ip address of the raspberry is written in the loaded VNC program. The rpi's default username is "pi" and default password is "raspberry". You can change default password and username for security.