The LDS garment is worn under regular clothing, both night and day, and is only to be removed for specific activities such as swimming, sports, etc and should be replaced as soon as possible.
Wearing the garment is a symbol of our covenants made with the Lord.
"The white garment symbolizes purity and helps assure modesty and respect for the attributes of God".
Wearing of the LDS garment brings blessings to those who worthily and faithfully keep the covenants they have made in the temple.
"Once people are endowed, they have the blessing of wearing the temple garment throughout their lives. They are obligated to wear it according to the instructions given in the endowment. Those who have been endowed in the temple must remember that the blessings that are related to this sacred privilege depend on their worthiness and their faithfulness in keeping temple covenants" ("Gospel Topic: Temples," Wearing the Temple Garment, LDS.org.)
As stated in the quote below, the LDS garment is to be treated with respect, not shown to others who do not understand it, and not modified in any way.
"The garment provides a constant reminder of the covenants made in the temple. The garment should be treated with respect at all times. It should not be exposed to the view of those who do not understand its significance, and it should not be adjusted to accommodate different styles of clothing. When worn properly, the garment provides protection against temptation and evil. Wearing the garment is an outward expression of an inward commitment to follow the Savior" ("Gospel Topic: Temples," Wearing the Temple Garment, LDS.org.)
When wearing the garment modest clothing should be worn over this sacred mormon clothing and should thoroughly cover it. In the official manual from the Church of Jesus Christ of Latter-day Saints, "Preparing to Enter the Holy Temple," it states:
"The wearing of such a garment does not prevent members from dressing in the fashionable clothing generally worn in the nations of the world. Only clothing that is immodest or extreme in style would be incompatible with wearing the garment. Any member of the Church, whether he or she has been to the temple or not, would in proper spirit want to avoid extreme or revealing fashions" (Preparing to Enter the Holy Temple, 1.)
"It should be understood that 'the things of the Lord' (2 Ne. 4:16) have included sacred clothing from the very beginning of this world. The scriptures contain many references to the wearing of special garments by the ancients. Prior to their expulsion from the Garden of Eden, Adam and Eve were clad in sacred clothing. We read: 'Unto Adam also and to his wife did the Lord God make coats of skins, and clothed.
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