What is solenoid? What does the divergence of magnetic field lines near the ends of a current-carrying straight solenoid indicate?

A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is called a solenoid.
The divergence of magnetic field lines near the ends of a current-carrying straight solenoid indicate a decrease in the magnetic field strength near the ends of the solenoid.

Fig.: Magnetic field lines around a current carrying solenoid