Wipe, in a computing context, means  to render all data on a hard drive unreadable. The term is often used in reference to making data stored on a computer, smartphone or tablet inaccessible before disposing of the device.
A semantic HTML tag is one that defines a meaning to the enclosed content that a computer can be programmed to understand. In most cases, browsers create some visual difference to content in semantic tags, for example, content in the CODE element is usually displayed in a monospaced font. But this is not a requirement. Many people feel that semantic HTML elements are a waste of bandwidth.
Elements can also have content, including other elements and text. Many HTML elements represent semantics, or meaning. For example, the title element represents the title of the document. In the HTML syntax, most elements are written with a start tag and an end tag, with the content in between. An HTML tag is composed of the name of the element, surrounded by angle brackets. An end tag also has a slash after the opening angle bracket, to distinguish it from the start tag.