Translation basically means putting the text content of a document into another language. Most documents these days exist in some electronic format. The large majority of these electronic documents contains formatting information, which rules the layout of the document.
Since most translators today use tools to handle their translations, such as e.g. a translation memory, some source documents need to be converted into a processable format that the translation tool can accept. Only some translation tools process the text independently of the formatting. This conversion process largely eliminates formatting and other non-textual information and leaves only the translatable part (i.e. the pure text) for processing in the translation tool.
So, how does the formatting information get back into the text after translation?