Phishing involves attempting to acquire sensitive information like usernames, passwords, and credit card details by masquerading as a trustworthy entity. It is often done through email spoofing or instant messaging to direct users to fake websites. Common phishing techniques include disguised email links and sender addresses, clickable email images leading to bogus websites, and requests for sensitive info. Users can prevent phishing by not responding to unsolicited requests for personal info, directly visiting websites instead of clicking links, monitoring accounts regularly, and being cautious with personal data.