Since web browsers and web servers operate at the application layer, we barely notice whether we are using encrypted or unencrypted connections. Web browsers use the URL convention of replacing “http:” with “https:” to indicate that the browser is to communicate with the web server using the Secure Transport Layer instead of the unencrypted Transport layer. Your browser will usually show a “lock” icon in the address bar to let you know that you are communicating with a secure web site.
There is a small overhead in setting up the https connections and a small cost to encrypt and decrypt the data that is being sent.
Since https was slightly more costly, for a while it was used only for pages that contained passwords, bank account numbers, or other sensitive data.
But over time as networks have become faster and the https implementations have gotten much more efficient, there is a trend toward encrypting all web server interactions whenever you are interacting with a web server where you have an account. The current trend is towards using https for all web traffic.