It's quite easy to get the similar-looking werden, wurden and würden confused, so we're taking a look today at the differences between them and the different contexts in which they are used.
To start with, wurden and würden are different grammatical moods of the verb werden.
Heute in unserer ersten Lektion werden wir die Buchstaben des deutschen Alphabets lernen.
Today in our first lesson, we will learn the letters of the German alphabet.
Caption 2, Deutsch mit Donna Blitz - Das Alphabet
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Es soll bis über zwanzig Grad warm werden.
It should get warm, up to more than twenty degrees.
Caption 16, München - 180. Oktoberfest eröffnet
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Schön, du musst mich nur küssen und dann werde ich eine wunderschöne Prinzessin.
Fine, you only have to kiss me and I will turn into a beautiful princess.
Caption 11, CHoE Rocker - Hunde-Prinzessin
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Die Tage werden immer kürzer und immer kälter.
The days steadily become shorter and colder.
Caption 9, Alpenseen - Kühle Schönheiten
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Oh, es wird sehr schwierig werden, meinen Titel zu verteidigen.
Oh, it is going to be very difficult to defend my title.
Caption 23, Wintersport - 7. Austrian Freeski Open
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As you can see, werden can be used in a wide variety of contexts and can be translated variously as "will," "get," "will turn into," and "become." The last example uses the future tense of the verb, wird werden, which is translated as "going to be."
In contrast, wurden is the Indikativ mood (similar to the indicative or realis mood in English) of werden. This just means that the verb is used to express a known state of affairs.
Sie flohen aus dem Königreich und wurden nie wieder gesehen.
They fled from the kingdom and were never seen again.
Caption 85, Märchen - Sagenhaft - Das tapfere Schneiderlein
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Here, wurden gesehen is the passive voice of the German Präteritum, as is common with the combination of werden and a past participle.
Wahrscheinlich wurden sie im hohen Norden auf dem Eis für die Jagd verwendet.
They were probably used for hunting on the ice in the far north.
Caption 17, Unterwegs mit Cettina - Schlittschuhlaufen
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Thus, wurden is usually translated as "were," but it is also sometimes used in the same sense that the present tense werden is sometimes translated as "become." The sentence Aus Bauern wurden Arbeiter could be translated as "Farmers became workers," which has a very different verb structure but a similar meaning in the end.
Ähm, was würden Sie denn als ihre Stärken und Schwächen, ähm, beschreiben?
Um, what would you then, um, describe as your strengths and weaknesses?
Caption 34, Eva erklärt - Bewerbungen
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Genau. -Würden Sie uns vielleicht 'n bisschen Ihren Stand vorstellen?
Exactly. -Would you maybe present your stand to us a little bit?
Caption 47, Unterwegs mit Cettina - auf dem Bruchsaler Weihnachtsmarkt
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Thus, würden is in most contexts translated to English as "would."
Further Learning
Watch the Yabla video about the verb werden, which goes into detail about the verb's conjugation, moods, and tenses, and go to Yabla German and see many other examples of werden, wurden, and würden used in a wide variety of contexts.