Constraints like a talisman halt the lifestream and preserve the existence of cursed objects while preventing them from doing any further damage. Cursed objects are often found wrapped inside talismans as a method of sealing them. The concept is to fend off poison with poison by using one curse to seal another. However, this is an outdated sealing method because after many years the seal weakens and changes form, eventually helping the cursed object attract curses and feed on them.
Talismans are commonly used on many different jujutsu-related items. The first of Sukuna's finger that Yuji found, all commissioned curtains, and Prison Realm are all cursed objects sealed with this type of constraint. The isolation chamber at Tokyo Jujutsu High. is also completely sealed off with hundreds of paper talismans.
Talisman can also be used for purposes outside of sealing. They can be used as an intermediary to conjure shikigami or they can be placed on curses to keep tabs on them. During the Kyoto Sister-School Goodwill Event, talismans were placed on the curses so when they were exorcised, the corresponding talisman also disappeared. Using cursed energy they were able to make arrangements so any exorcisms made by Tokyo burned red and any by Kyoto burned blue.