How did travelers comunicate with the people of a foreign country? Did they hire someoje to translate? How many bilingual people existed to do such a job? And what if you travelled to countries where rarely anybody who could speak your language would go to?
This post has been removed as a "throughout history" type of question. If there's a particular culture/region and time period of interest, do feel welcome to repost. Meanwhile, you may find something useful in the FAQ