The four cups are derived from four expressions of redemption found in Exodus 6:6-7: "I will bring you out;" "I will deliver you;" I will redeem you;" and "I will take you." Let each of our cups represent a current group that needs to be "brought out, delivered, redeemed or taken out."

Four Questions of Modern Day Slavery
Religious Action Center
Why on this night are some people still enslaved today?
Why on this night do so many remain hungry in the world?
Why on this night do we invite the hungry and lonely to share our meal?
How can we eradicate hunger and homelessness tonight and every night?
A fifth question can be posed: "Why is this night no different from other nights? Because on this night millions of human beings around the world still remain enslaved, just as they do on all other nights. As a celebration of our freedom, we remember those who remain enslaved."

haggadah Section: -- Four Questions
Source: Religious Action Center