JavaScript is effectively a language without which modern websites are hard to imagine. If you're running a business and thinking about developing an online presence, understanding what JS can do will help you make more informed technology decisions. Today, it is responsible for many elements - from simple animations to full-fledged web applications. You need an interactive form with validation and CRM enrollment, a cost calculator that takes into account different rates and discounts, a reservation system with calendar and payments or an online store - these are typical examples where JS is sometimes crucial, although it seems that you don't always need to complicate the solution right away. Modern frameworks like React, Vue or Angular have changed the way we build admin panels, CRMs or analytics dashboards and allow us to create fast, responsive interfaces. On the other hand, probably not every company needs the latest stack right away - sometimes a simple, well-written script is enough, and using too many libraries can suggest unnecessary load on the site. JavaScript also gives you the ability to create Progressive Web Apps - apps that run like native apps on a phone without installation, which can sometimes be economical, although it won't replace all the features of a native app. Here you'll learn how JS affects site performance, what solutions will work for specific business cases, and how to work with developers to get exactly what you need.