EmailJS is a service that allows users to send emails directly from their client-side applications. By integrating with popular email systems like Gmail, Yahoo, Outlook, and others, EmailJS facilitates sending emails using only client-side technologies without requiring a server component. This makes it particularly useful for developers looking to implement email functionalities in web and mobile applications without handling server-side code. EmailJS provides various templates and customizable options to streamline the process, and it ensures secure communication by keeping API keys and user data protected.