What is font shape engine and font layout engine?

Question

Also it will be good to have a list of open source libraries which does layout & shaping.

Answer 1

Below links explains clearly.

1. http://behdad.org/text/
2. http://userguide.icu-project.org/layoutengine
3. http://www.panl10n.net/Presentations/Cambodia/Pema/LocalizationofLinux(Bhutan).pdf