Web Development is the technical process of building, coding, integrating, testing, and maintaining websites and web applications.
It matters because development decisions affect speed, security, scalability, tracking, SEO, and maintenance. A site that looks good but is fragile or hard to update can quietly hold back every marketing channel.
Example
A retailer needs live stock levels on its product pages. Web development connects the inventory system, renders availability, handles failures, and tests checkout so an attractive product page also supports a working purchase.