Here are some basic definitions for malicious content found in emails and web pages/sites.
Adware: As defined by Wikipedia: “Adware, or advertising-supported software, is any software package that automatically renders advertisements in order to generate revenue for its author. The advertisements may be in the user interface of the software or on a screen presented to the user during the installation process. The functions may be designed to analyze which Internet sites the user visits and to present advertising pertinent to the types of goods or services featured there. The term is sometimes used to refer to software that displays unwanted advertisements known as malware.”
Malware: As defined by Wikipedia. “Malware, short for malicious software, is any software used to disrupt computer operations, gather sensitive information, gain access to private computer systems, or display unwanted advertising.”
Phishing: As defined by the Searchsecurity.techtarget.com web site. “Phishing is a form of fraud in which the attacker tries to learn information such as login credentials or account information by masquerading as a reputable entity or person in email, IM or other communication channels. Typically a victim receives a message that appears to have been sent by a known contact or organization. An attachment or links in the message may install malware on the user’s device or direct them to a malicious website set up to trick them into divulging personal and financial information, such as passwords, account IDs or credit card details. Phishing is a homophone of fishing, which involves using lures to catch fish.”
Spyware: As defined by Wikipedia: “Spyware is software that aims to gather information about a person or organization without their knowledge and that may send such information to another entity without the consumer’s consent, or that asserts control over a computer without the consumer’s knowledge. This includes Trojans, which is defined separately below.”
Trojan (horse) virus: As defined by Webopedia. “One of the most insidious types of Trojan horse is a program that claims to rid your computer of viruses but instead introduces viruses onto your computer. The term comes from a Greek story of the Trojan War, in which the Greeks give a giant wooden horse to their foes, the Trojans, ostensibly as a peace offering.”
Viruses: As defined by Wikipedia: “A computer virus is a type of malicious software program (“malware”) that, when executed, replicates by reproducing itself (copying its own source code) or infecting other computer programs by modifying them. Infecting computer programs can include as well, data files, or the “boot” sector of the hard drive. When this replication succeeds, the affected areas are then said to be “infected” with a computer virus.”