usccb.org/liturgy/current/chapter2.shtml#sect2
If you would like to read more click on the link taken from the General Instructions of the Roman Missal
Here is the excerpt regarding *Movements and Posture
*42. The gestures and posture of the priest, the deacon, and the ministers, as well as those of the people, ought to contribute to making the entire celebration resplendent with beauty and noble simplicity, so that the true and full meaning of the different parts of the celebration is evident and that the participation of all is fostered.52 Therefore, attention should be paid to what is determined by this General Instruction and the traditional practice of the Roman Rite and to what serves the common spiritual good of the People of God, rather than private inclination or arbitrary choice.
A common posture, to be observed by all participants, is a sign of the unity of the members of the Christian community gathered for the Sacred Liturgy: it both expresses and fosters the intention and spiritual attitude of the participants.
- The faithful should stand from the beginning of the Entrance chant, or while the priest approaches the altar, until the end of the Collect; for the Alleluia chant before the Gospel; while the Gospel itself is proclaimed; during the Profession of Faith and the Prayer of the Faithful; from the invitation, Orate, fraters (Pray, brethren), before the prayer over the offerings until the end of Mass, except at the places indicated below.
They should, however, sit while the readings before the Gospel and the responsorial Psalm are proclaimed and for the homily and while the Preparation of the Gifts at the Offertory is taking place; and, as circumstances allow, they may sit or kneel while the period of sacred silence after Communion is observed.
In the dioceses of the United States of America, they should kneel beginning after the singing or recitation of the
Sanctus until after the
Amen of the Eucharistic Prayer, except when prevented on occasion by reasons of health, lack of space, the large number of people present, or some other good reason. Those who do not kneel ought to make a profound bow when the priest genuflects after the consecration. The faithful kneel after the Agnus Dei unless the Diocesan Bishop determines otherwise.53
With a view to a uniformity in gestures and postures during one and the same celebration, the faithful should follow the directions which the deacon, lay minister, or priest gives according to whatever is indicated in the Missal.
- Among gestures included are also actions and processions: of the priest going with the deacon and ministers to the altar; of the deacon carrying the Evangeliary or Book of the Gospels to the ambo before the proclamation of the Gospel; of the faithful presenting the gifts and coming forward to receive Communion. It is appropriate that actions and processions of this sort be carried out with decorum while the chants proper to them occur, in keeping with the norms prescribed for ea
