dimension compacification

[pramodmaths]

Being a graduate student,I want to know why we make compactification?
As a simple case of two dimensions if we consider all the conic sections
on our palm and try to see this from a line side(1 d visualization),we see
an interval of the real line.All other informations are lost.Similarlly, in string
theory compactification also a lot of informations may be lost.Then how we
can say,o.k., we will get them back?

[AntonioLao]

I want to know why we make compactification?

The way I see this is that compactification is a method of arriving at solutions. Given two straight lines on the x-y plane of a given Euclidean geometry, if the lines intersect then there is a unique point solution.