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  "body": "\n## Summary\n\nA Gromov–Witten invariant is a rational number that counts curves in a smooth projective variety or a symplectic manifold.\nThe curves have a given genus and homology class, and they pass through given cycles.\nIt is defined by integrating cohomology classes over the virtual fundamental class of a [[moduli space|FJZRW9P0K3]] of stable maps.\nThese invariants solve classical questions of [[enumerative geometry|ZPZA1FKZZC]], they define quantum cohomology, and they are one side of [[mirror symmetry|YK3DMN2NSK]].\n\n## Explanations\n\n### L1 human\n\nAsk how many curves of a fixed kind pass through a fixed set of points.\nFor lines in the plane through two points the answer is $1$, for conics through five points it is also $1$.\nFor rational plane cubics through eight general points the answer is $12$.\nGromov–Witten invariants give a uniform way to define and compute such numbers, by integrating over a space that parametrizes all the curves at once.\nThey stay the same when the variety is deformed, which makes them invariants.\n",
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