In 5E inspiration can be given to a player for moments of good RP, creating interesting/ fun situations, or just if the DM thinks they did something cool. Inspiration can be spent to give yourself advantage on a roll but you must decide before rolling. I like to be more liberal with inspiration if people are doing cool things, so it's not just a thing you either have or don't that is rarely distributed that can be used once for a low reward. Instead you can stock up inspiration points and use them like that, or in these additional ways:
- 1 point to give yourself advantage before making a roll.
- 2 points you can give disadvantage to someone's roll or cancel out their advantage before it is made.
- 3 points you can retcon a roll you don't like the results of and force a re-roll after it's happened.
- 5 points you can take an extra standard action this turn.
Obviously as these points are generally rewarded for cool RP moments, it's rad if when you use them you can explain an RP reason why the thing happens, but it's not required. Just cool. ;)