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  "body": "\n## Summary\n\nAn open immersion is a [[morphism of schemes|JXRKH6P1Z4]] that identifies its source with an open subscheme of its target.\nOpen immersions are the maps used to glue schemes and to restrict a scheme to an open subset.\nThe basic example is the inclusion of a basic open set $D(f) = \\operatorname{Spec} A_f$ into $\\operatorname{Spec} A$.\n\n## Explanations\n\n### L1 human\n\nAn open immersion is the inclusion of an open part of a scheme, carrying the same functions as the big scheme there.\nRemoving the origin from the line gives an open immersion of $\\operatorname{Spec} k[x, x^{-1}]$ into $\\operatorname{Spec} k[x]$.\nOn the open part, the function $1/x$ is allowed, because $x$ is never zero there.\nEach chart of projective space is an open immersion of affine space into it.\n",
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