Fitts’s Law, formulated by psychologist Paul Fitts in 1954, is a predictive model of human movement that is widely applied in user interface (UI) design. The law states that the time required to move to a target area, such as a button or link, is a function of the distance to the target and the size of the target. In simpler terms, larger and closer targets are quicker and easier to hit, while smaller and farther targets take more time and effort.

Jakob’s Law, proposed by usability expert Jakob Nielsen, states that users spend most of their time on other websites and prefer your site to work the same way as the sites they already know. In essence, users' familiarity with other websites influences their expectations and behaviours when they visit your website. Understanding and applying Jakob’s Law is crucial for designing intuitive and user-friendly interfaces.

A website's design system is a comprehensive set of standards for managing design at scale using reusable components and patterns. It includes guidelines, style guides, UI components, and coding standards that ensure a consistent visual language and user experience across a website. Implementing a robust design system is crucial for maintaining brand coherence and enhancing brand perception.