The <base> tag specifies the default address or default destination for all links on the page. Normally, the browser will extract the corresponding element from the URL of the current document to fill in the blanks in the relative URL. use
The <base> tag can change this. The browser will then no longer use the URL of the current document, but use the specified base URL to parse all relative URLs. This includes URLs in <a>, <img>, <link>, <form> tags. Quote 2: target is the target page you jump to after clicking on the link.
In layman's terms, it is the link on your current page, including <img>, <link>, and <form>. Unless you specify a target, such as <a heft= target=_blank> link, it will be opened in _self (this page) according to the provisions of <base target=_self>. This base target= can also be top, _blank, parent or other frame names.