Ngram Viewer by google is a very useful tool for certain situations. It is a search engine which stores thousands of digital documents to show graphs comparing terms according to their frequency of use. If we want to use it to compare how apparently popular some musician is compared to another, it will do the trick. Notwithstanding, this is of no use to us translators. But what if you are doubting between nursery school, kindergarten and childcare? By typing these three options into the search bar, a graphic will appear showing the frequency of use of each of these terms over time.
Sometimes, especially when translating into a language that it is not our mother tongue, we doubt whether this or that term is more appropriate. This is a good start. As long as we have checked that all of these terms are equal in meaning, we will want to get rid of the old-fashioned ones. You can also try fixed expressions to check how well they work together. For instance, if you are doubting between “to my surprise” and “in my surprise”, just type them on this search bar and you will see that only the first one works.
Moreover, when tackling technical terms and we find more than one possible translation, this tool will help you find which one is more common, and therefore make the text work smoothly. This tool has helped me on numerous occasions but I never take it as the only check. This comes after having painstakingly researched into the topic and still you are not sure which term is widely understood and which ones might be old-fashioned. You have to take into account various factors: Are the terms I want to compare used in other contexts? (this may give one of the terms more prevalence but it does not mean it would work better in the target text) Are the terms or expressions equal in meaning? Am I writing something for a large audience or should I select more formal words with a lower frequency of use? Ngram your doubts as a reference, but the final decision is yours alone. As with any other translation resource, the filter of common sense must prevail.