HTML : HTML (HyperText Markup Language) is a markup language interpreted by web browsers, that is, the skeleton of all websites. Its newest version is HTML5, which contains semantic tags to write clean code and has advantages as native support for audio and video.
Javascript : Javascript is a programming language that runs on the client-side (in the browser) and in most cases is used to make a website interactive.
Accessibility : It refers to the correct display of a website on all devices. It is relative to the concept of ‘Responsive web design’ that is achieved by adding CSS Media Queries that respond to the width of the screen or viewport.
Usability : It refers to the relationship between the user and the ease with which he manages to navigate the site.
CSS : CSS (Cascading Style Sheets) is the language that controls the appearance of the site, that is, with which you will give your HTML the visual style, defining colors, sizes, fonts, and even mouse events. Its latest version is CSS3, which supports natively, animations, shadows, curves etc.
PHP : PHP is a programming language that runs on the server, this means that it makes queries to return data, in this language dynamic and manageable websites are created.
SEO : SEO (Search Engine Optimization) refers to the proper indexing that search engines such as Google, Bing, Yahoo, etc., make of a website to rank well in the search results. This is achieved through meta tags, titles and the correct use of keywords.
Performance : It must load fast because if users notice a low performance in load times, they will surely leave the website.