Before you start learning ethical hacking there are some terms you should definitely know about them.

Hack Value - The term hack value refers to a value that denotes attractiveness, interest or something that is worthy. Value describes the target's level of attraction to the hacker.

Zero Day Attack - Zero day attack refers to threats and vulnerabilities that can exploits the victim before the developer identify or address and release any patch for that vulnerability.

Vulnerability - The vulnerability refers to a weak point, loophole or a cause in any system or network which can be helpful and utilized by the attackers to go through it. Any vulnerability can be an entry point for them to reach the target.

Daisy Chaining - Daisy chaining is sequential process of several hacking or attacking attempts to gain access to network or systems, one after another, using the same information and the the information obtained from the previous attempt.

Exploit - Exploit is a breach of security of a system through Vulnerabilities, Zero-Day Attacks or any other hacking techniques.