Shimenawa is a rope made by twisting together stands of rice straw
and a sighn to indicate the boundary of a sacred place and set it off from the realm of the profan

1: for the New Year 2: goshimboku/a holy tree 3: shinto shrine

Huge shimenawa of Izumo -Taisha (shrine)

They are hung on the shrine buildings (pic. 3), sacred gateways (torii) etc.
to distinguish between secular and sanctified areas and to ward off evil.
They are also hung around sanctified objects like very big old trees (pic. 2) or large rocks
in which the spirit of a deity is thought to repose..

Special shimenawa are made at New Year's.
They are decorated with various auspicious objects (pic.1).

kamishide/pieces of white paper ( to alert )
daidai/bitter orange (symbol of prosperity of future generations)
lobster/Ise-ebi (symbol of longevity)
sasa-no-ha/leaves of a bamboo tree (symbol of energy)