What is meaning of Flag state?

In other words we can understand

Definitions of “flag  State”:-

“The State which has granted to a ship the right to sail under its flag”

OR

“The State whose nationality the ship possesses”

OR

“A State whose flag a ship flies and is entitled to fly”

NOTE:

• A State may assume a number of roles in a maritime context dependent upon its location, function, sovereignty, boundaries, and relationship with vessels of another State.
• The necessary elements of a flag State in international law are for a State to have granted ships its nationality through the registration process and to effectively exercise its jurisdiction and control over those ships in administrative, technical, and social matters, apart from where treaty provisions deem otherwise.
• flag State clearly cannot exercise criminal jurisdiction through the “passive personality principle”, according to which, “aliens may be punished for acts committed abroad harmful to nationals of the forum” nor the “protective security principle”, according to which, “nearly all States assume jurisdiction over aliens for acts done abroad which affect the security of the state.