The Swedish language has a long history of loaning words from other languages in Europe. Usually, the source languages have been of large economic or cultural importance for Sweden. This process of loaning words started around the 10th century AD, just a century after historians consider the Swedish language to have become a language of its own, different from the other Nordic languages.
The deciding factor for the start of this process was the entrance of Christianity into Sweden during the century 900 AD. The growing population of converted Christians created strong cultural ties with the rest of Christian Europe. During this time, many words were borrowed from the Latin and Greek languages, including mässa (mass), kyrka (church), and biskop (bishop).
Soon thereafter, an influx of German tradesmen found Sweden an appealing place to trade goods. For approximately five hundred years (1000-1500, the entire Middle Ages), the Low German language left a strong and very visible mark on the Swedish language. (This was German’s strongest period in Sweden; words continued to be borrowed from German until the early 1900′s.) Words such as arbete (arbeit/work), bliva (bliven/to become, nowadays said and written bli), and möjlig (möglich/possible), among many others, were introduced into the Swedish language. On top of that, many suffixes and prefixes were also loaned - betala (to pay), erbjuda (to offer), följning ([a] following) – and even the Swedish word order was affected.
(Keep in mind that Swedish has always been a Germanic language, even before the arrival of Low German in the country. What today is known as German is considered to be a West Germanic language and Swedish a North Germanic language.)
The next language to make its mark on the Swedish language was French, which began its influence in the 17th century and continued throughout the 1700′s. Examples of loans from French in Swedish are vag (vague/vague), enorm (énorme/enormous), and fåtölj (fauteuil/armchair). During its time of influence in Sweden, as it did in much of Europe, the French language became the language of diplomacy.
And finally, since around the end of World War II, English has been the language of interest in Sweden. Words like eskalera (escalate), tuff (tough), and webb (web, as in Internet) have made their way into the Swedish vocabulary. Even today, English is the largest language of influence in Sweden – schoolchildren start learning English as a mandatory school subject as early as the first grade. Today, if you visit Sweden, almost anyone you talk to will be able to speak to you in English. But don’t let that stop you from learning Swedish – it is a beautiful language that has a lot to offer, and an absolute must if you intend to live in Sweden!
As an honorable mention, I should include that Sweden’s five official minority languages have had their turn as well. Words such as pojke (boy) and pjäxa (ski boot) come directly from Finnish (poika and pieksu, respectively); tjej (girl) and haja (to understand, to ‘get it’) both come from Romani (Gypsy). The other three official minority languages of Sweden are Meänkeli, Sami, and Yiddish.