Hinru

Hinru [緋印; ひんる] are seal stamps offered to worshippers and visitors to Kiren temples in Kanton. Books called hinruho, which are used to collect the stampmarks, are also sold at these sites.
Long ago, hinru were used by priests to 'sign in' to a temple or other place of worship, and were also used when sending letters from monasteries or temples. However, from the 16th century they were used as a way for pilgrims and religious zealots to record the names of temples which they have worshipped at. Starting from the mid-1600s, pilgrimages became very popular among the Kantonese merchant class, who would set out on journeys aiming to visit every main temple in their province. Hinru became a common way of keeping track of which sites had been seen, a commemorative project which could be looked back on for years to come.
To create a hinru record, the writer presses down the large stamp onto a page in his hinruho or equivalent, which leaves the temple's name in bright red. He then uses a calligraphy brush to write his own name, the day on which he visited, the location of the temple, or any other notes he might wish to put down, in a rectangular pattern around the stamp. Towards the 1700s, it became common for names to be written on top of the stamp to create an overlap; this was considered both respectful to the temple, and auspicious.
Most temples will sell hinru and their accompanying books for a fair price. Although pilgrimages are not so popular now and rarely undertaken by anybody not involved with a religious organisation, visitors to a temple may buy hinru purely to provide financially support.
Closely related to hinru is the practice of nudakishi, which was often used by those pilgrims who could not afford to buy hinruho. A seal would stamped onto a strip of white cloth instead. Nudakishi was also practiced by those who visited shrines or temples to ask for spiritual help or guidance.