Inductance
A coil's resistance to changing current. The voltage across it is L x change in I / change in t. It stores energy 1/2 L I squared.
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Analogy
A heavy flywheel for current.
Example
V = L x change in I / time= 2 x 3 / 0.5= 12 V
In practice
A 2 H inductor with current changing by 3 A in 0.5 s has 12 V across it.
Questions people ask
Why does an inductor resist sudden changes in current?
A changing current changes its own magnetic flux, which induces a voltage that opposes the change, as Lenz's law says. So current cannot jump instantly. This is why switching off a coil can make a spark, because the field collapses quickly and produces a large voltage.
Where is energy stored in an inductor?
In the magnetic field inside the coil, with energy 1/2 L I squared. When the current falls, the field shrinks and returns the energy to the circuit. This is similar to a capacitor storing energy in its electric field, but with current in place of voltage.