在数学中，外推是指从已知数据的孤点集合中构建新的数据的方法。与内插类似，但其所得的结果意义更小，而且更加受不确定性影响。

在市场学中，这种方法被用来预测未来产业走向。

在网络营销中,外推是SEO中的一种，主要是通过在分类信息、论坛、B2B平台等来发布与自己所要推广的产品有关系的信息，因为分类信息网站，论坛，B2B平台等的权重一般都比较高，发布的信息容易获得较好的排名，同时在外推信息中带的链接又可以作为网站的一个入口，吸引更多的流量，且信息数量足够多的时候可以达到覆盖关键词的目的。

In mathematics, extrapolation is the process of estimating, beyond the original observation range, the value of a variable on the basis of its relationship with another variable. It is similar to interpolation, which produces estimates between known observations, but extrapolation is subject to greater uncertainty and a higher risk of producing meaningless results. Extrapolation may also mean extension of a method, assuming similar methods will be applicable. Extrapolation may also apply to human experience to project, extend, or expand known experience into an area not known or previously experienced so as to arrive at a (usually conjectural) knowledge of the unknown (e.g. a driver extrapolates road conditions beyond his sight while driving). The extrapolation method can be applied in the interior reconstruction problem.