Hot is a slang-based reference that essentially likens the amount of attraction, talk or interest in someone or something to the generation of heat.
Hot frequently is used to describe physical or sexual attractiveness — thus the prevalence of terms such as "hot guys" or a "hot women." The term is also used in rating a person's sex appeal by classifying them as "hot or not." As a tag, hot can also be used to refer to any number of things in which there is growing or fervent excitement or interest, whether it be music, technology, gadgets or even urban legends.
Technorati helps users keep track of what's hot on the Internet by providing information on what's popular not only in blogs but what topics on the Internet have rising interest levels and topics in which interest is falling.