HTTPS is the secure version of HTTP that uses encryption to protect data exchanged between browsers and websites.
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 contact form submits over HTTPS so the connection encrypts data in transit. The site still needs secure handling and storage after submission because transport encryption does not protect every later use of that information.