You've probably noticed that gingerbread or honey cake stays soft far longer than a plain Bundt cake. Honey deserves much of the credit, since it naturally binds moisture.
Liquid invert sugar works on a similar principle to honey — it helps hold on to moisture and keeps baked goods soft for longer. The difference is that it's flavour-neutral, so it won't change the taste or colour of your bake.
That makes it perfect for macarons, sponges or ice cream, but you can just as easily stir a small amount into gingerbread or honey cake too. Honey brings the signature flavour, while invert sugar boosts the softness.