God is the only source of Revelation. The Deposit of Faith is the truth of God's Revelation as expressed in Sacred Scripture, which is the inspired and written Word of God, and Sacred Tradition, which is the Word of God as taught and transmitted through the teaching authority of the Church.
There exists a close connection and communication between Sacred Tradition and Sacred Scripture. For both of them, flowing from the same divine wellspring, in a certain way merge into a unity and tend toward the same end. (DV 9; cf. CCC 86, 97)
Sacred Scripture is the Word of God, written under the inspiration of the Holy Spirit, contained in the collection of sacred books that have God as their true author and are entrusted to the Church (cf. DS 3006).
Sacred Tradition from the Latin traditio, meaning "to hand on") is the Word of God as received from Christ himself through the Apostles and transmitted to us without aIteration—as it were, from hand to hand—by the Church with the assistance of the Holy Spirit (cf. DS 1501; DV 9). Sacred Tradition must not be confused with "traditions" of a pious, devotional, theological, or disciplinary nature. (Cf. CCC 76-78, 81-83,2033)
Both Sacred Scripture and Sacred Tradition are to be regarded with equal reverence and devotion. Sacred Tradition preceded the New Testament writings; the first Christians had no written Gospels and only the preaching of the Apostles, the oral tradition, to instruct them about Christ and his teachings. Through Tradition we know which books are inspired by the Holy Spirit, that is, the list, or canon, of the books that make up Holy Scripture. (Cf. CCC 83)
Testimonies of Tradition date back to the first centuries and have been preserved in either ancient liturgical or disciplinary texts and practices or the writings of early Christian authors. (Cf. CCC 120,175)
-The Didache Bible
Apostolic Tradition is the transmission of the message of Christ, brought about from the very beginnings of Christianity by means of preaching, bearing witness, institutions, worship, and inspired writings. The Apostles transmitted all they received from Christ and learned from the Holy Spirit to their successors, the bishops, and through them to all generations until the end of the world.
Apostolic Tradition occurs in two ways: through the living transmission of the word of God (also simply called Tradition) and through Sacred Scripture which is the same proclamation of salvation in written form.
Tradition and Sacred Scripture are bound closely together and communicate one with the other. Each of them makes present and fruitful in the Church the mystery of Christ. They flow out of the same divine well-spring and together make up one sacred Deposit of Faith from which the Church derives her certainty about revelation.
-Compendium, 14. CCC
The Apostles entrusted the deposit of faith to the whole of the Church. Thanks to its supernatural sense of faith the people of God as a whole, assisted by the Holy Spirit and guided by the Magisterium of the Church, never ceases to welcome, to penetrate more deeply and to live more fully from the gift of divine revelation.
-Compendium, CCC
The task of giving an authentic interpretation of the deposit of faith has been entrusted to the living teaching office of the Church alone, that is, to the successor of Peter, the Bishop of Rome, and to the bishops in communion with him. To this Magisterium, which in the service of the Word of God enjoys the certain charism of truth, belongs also the task of defining dogmas which are formulations of the truths contained in divine Revelation. This authority of the Magisterium also extends to those truths necessarily connected with Revelation.
-Compendium, CCC
Scripture, Tradition, and the Magisterium are so closely united with each other that one of them cannot stand without the others. Working together, each in its own way, under the action of the one Holy Spirit, they all contribute effectively to the salvation of souls.
God has revealed himself to us so that we might have faith in Jesus Christ and the One who sent him. It is through God’s grace that we have the gift of faith. The Deposit of Faith contained in Sacred Scripture and Sacred Tradition nurtures our growth in faith and teaches us how to live as Christ’s disciples.
-The Catholic Faith Handbook