A front-end developer will have core strengths in three ‘languages’: HTML, JavaScript, and CSS - which are introduced in the next few sections of the Guide. They complement each-other and are usually used in combination.
Even so, knowing HTML, JavaScript, and CSS to a useful degree is still only the basis of a front-end developer’s role. Imagine that being a front-end developer is akin to being a furniture-maker. In that case proficiency in HTML, JavaScript, and CSS is akin to knowing how to correctly operate a saw, hammer, and paint-brush. All of these things are tools of their respective trade, and knowing how they work is essential. However, in order to make a decent wardrobe a furniture maker must know more than how their tools work, there are other skills that must be learned; joint making, structural design, finishing techniques, etc. Likewise, in order to make a decent website there are skills beyond understanding HTML, JavaScript, and CSS. These three languages are foundation skills and as a front-end developer it’s important to know each - but the real mark of competence and craftsmanship is knowing how to use and combine them effectively for each specific website.