1. Go outside.
2. Find a perennial plant (like this Sedum).
3. Look at the base of it.
Perennials are so called because they come back into growth every year after dying off at the end of the previous growing season. Some wither and fade by themselves each autumn. Some will get blown apart by autumn winds, others disintegrate in January ice. Others have stems and flowerheads robust and woody enough to withstand the worst of winter and last right through to spring.
Some of them have an interesting or attractive enough appearance to be worth leaving them there over the winter. Although they are dead, they provide some structure when everything around them has shrunk back into the ground. They can look beautiful on frosty mornings when covered in icy crystals, and they add texture to an otherwise potentially bland wintry scene.
Now is the time to remove the remnants of last year and start looking forward to everything the garden has in store for you this year. Just cut the old stems right back to the ground and enjoy the fresh bright growth left behind as it takes over, giving hope for the coming year as the garden gets going again.