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.
An HTML file consists of text, that is, the words that you want to appear in your document and embedded instructions called HTML tags. The tags give the browser instructions that include formatting, display of images, and hyperlinks. The technical name for the type of data in an HTML file is ASCII text.