The tutorial by Kumar Harsh outlines the implementation of passkey authentication as a secure alternative to traditional passwords, leveraging public-key cryptography to enhance security and user experience. Passkeys use a unique key pair system, with a private key stored on the user's device and a public key shared with websites, to authenticate users without exposing sensitive information even if the website is compromised. The guide details both the complex process of implementing passkeys from scratch and the simpler method using Descope, a no-code platform that allows drag-and-drop integration of authentication flows. Descope simplifies the process by providing a visual interface for setting up authentication logic, making it accessible for developers of all skill levels to integrate secure login processes. The tutorial also highlights the advantages of using libraries like SimpleWebAuthn and Descope to manage the intricacies of server-side setup, client-side integration, and user management, ultimately facilitating a seamless and secure user authentication experience.