Project FLY has the main objective of making the on-line edition and the interdisciplinary study of documents of the private sphere written in the first three quarters of the XXth century. The corpus is a sample of 2.000 letters from a universe of millions of epistolary originals. They were written in the contexts of war, migration, imprisonment and exile, in a time when members of all social classes became gradually literate. Until the end of 2014, the FLY project will offer to the public the electronic edition of 2.000 private letters from XXth century accompanied of sociology, historical and linguistic indexes.