Limbo comes from the Latin word limbus meaning "fringe" or "edge." Limbo, as what has been taught by the Catholic Church for generations, is considered to be "outside of heaven." The Catholic Encyclopedia defines "limbo of the fathers" as that state or reserve in which the souls of the just, such as Abraham, Isaac, and Jacob were detained until the complete redemption by Christ through which heaven was opened to them. This was the "paradise" spoken of by Christ in addressing the good thief at the crucifixion (Lk. 23:30-43).
On the other hand, "limbo of the children" is that state wherein the souls of unbaptized children and adults, who die without committing grievous actual sin, enjoy perfect natural happiness. Here, they are excluded from the supernatural excellence of heaven, namely, the vision of God, but they do know God and love Him with their perfected natural faculties.
This move by the Catholic Church is deemed by theologians as highly significant for what it means theologically about the Church’s views on heaven, hell and original sin. The main beneficiary of the Church’s announcement that limbo did not exist are the unbaptized children. First of all, newborn children have absolutely no say on whether they will be baptized or not. That is the decision of their parents and elders. The declaration that limbo is non-existent just confirms that the gates of heaven have always been open, even to unbaptized children. That is the way of God.
If there is one individual who did not get justice after he died, then there is no God. Those who were previously "in limbo" can now rejoice in salvation, especially the innocent.