: If you are using a plugin for galleries or sliders, the plugin might be malfunctioning and outputting raw code instead of the rendered image.

: This is "lazy loading," which instructs the browser to only download the image when it is about to appear on the user's screen (e.g., as they scroll down). This saves bandwidth and makes the initial page load much faster.

: You may have accidentally pasted HTML code into a "Visual" or "Rich Text" editor instead of a "Code" or "HTML" block.