Spear phishing is when an attacker targets a specific individual rather than sending a generic email to a group of people.
Spear phishing attacks try to specifically address the target and disguise themselves as a person the victim may know.
These attacks are easier for a scammer if you have personally identifiable information on the internet. The attacker is able to research you and your network to craft a message that is relevant and convincing.
Due to the high amount of personalization, spear phishing attacks are much harder to identify compared to regular phishing attacks.
They are also less common, because they take more time for criminals to pull them off successfully.