During the Paleolithic Era people were Hunter-Gatherers, which meant that they had to hunt to get their food. They also gathered plants. Hunter-Gatherers were nomads, which meant that they moved from place to place.
Now that we are not hunter-gathers we started planting crops and harvesting them.
Since we domesticate animals now, we have a reliable food source.
We have a surplus of food which means we can now specialize in other things!
Agriculture has enabled us to settle down in one place and we have control of our food.