SSH (Secure Shell) is a network protocol to connect remote computers securely. It is the simplest way to access your Raspberry Pi over the WiFi or Ethernet. However, Raspberry Pi does not allow SSH connections to itself by default. To enable SSH connection, create an empty "SSH" file with no file extension on the "boot" drive of the micro SD card.
To make the empty SSH file, open any text editor like Notepad, and save as the empty file as "SSH" name, without a file extension.
Now, safely remove the micro SD card from your computer. You're ready to go!