DefinitionLine integrals, in general, extend the idea of the integral to situations where the path of the integration matters throughout a region in the plane or space. Just as a definite integral is a number that gives us the area under a line with coordinates defined by a function, a line integral computes the sum of a scalar or a vector field along a specific curve. The line integral of a scalar field f(x,y) along a curve C, is written as ∫Cf(x,y)ds. Then with capital F being a vector field, this would be written ∫CF⋅dr. E.g. for the line segment path from (0,0) to (1,1) and field f(x,y)=x+y it would take the form ∫C(x+y)ds.