Replace elements:
The replacement element is the browser to determine the specific content to display according to the elements and attributes of its tag.
For example: <input /> type="text" is that this is a text input box. When you change it to another, the browser display will be different.
<img>, <input>, <textarea>, <select>, <object> in (X)HTML are all replacement elements, none of which have actual content.
Non-replaced elements:
Most elements of (X)HTML are non-replaceable elements, they tell the browser the content directly and display it.
For example <p>wanmei.com</p>
The browser will display this content directly.