a reversible reaction or mixture’s “happy place.” Dynamic equilibrium occurs when the forward and backward reaction rates equalize so that the amount of the forward reaction equals the amount of the backward and the overall proportions of reactants vs products doesn’t change over time (even though the forward and backward reactions can still occur.
So, for instance, if you have a binding interaction
A + B ⇌ AB
At equilibrium, the amount going to the right is equal to equal to the amount going to the left, so if you were to measure the concentrations of bound and unbound, they’d be stable even if there’s still some binding and unbinding going on.
If you leave any reaction be long enough it (with same temperature, etc.) it will eventually reach the same equilibrium no matter what you start with because that equilibrium is determined by inherent energetic interaction stuff (thermodynamic properties). Some reactions would take a really really long time to get there, but enzymes can help facilitate reactions allowing them reach equilibrium far faster (but the enzymes do not change the equilibrium you reach because they catalyze (speed up) the reaction in both directions).