1. Meaning of etymology
Etymology is the study of the history of words — when they entered a language, from what source, and how their form and meaning have changed over time.
In languages with a long detailed history, etymology makes use of philology, the study of how words change from culture to culture over time. However, etymologists also apply the methods of comparative linguistics to reconstruct information about languages that are too old for any direct information (such as writing) to be known. By analyzing related languages with a technique known as the comparative method, linguists can make inferences, about their shared parent language and its vocabulary. In this way, word roots have been found which can be traced all the way back to the origin of, for instance, the Indo-European language family.
Even though etymological research originally grew from the philological tradition, nowadays much etymological research is done in language families where little or no early documentation is available, such as Uralic and Austronesian.