Learn German: Die Sache ist wichtig. - The matter is important.

Sache is a very common word that translates to 'thing', 'matter', or 'issue'. You can use it to talk about physical objects, like your belongings, or abstract concepts, like a situation or a subject being discussed.

Why is there no ending on the adjective wichtig? Shouldn't it match the feminine noun die Sache?

In German, adjectives only get special endings when they come directly in front of a noun. When an adjective comes after a verb like ist, it stays in its basic dictionary form without any extra letters added.

If I want to add aber (but) or denn (because) to the start of this sentence, does the word order change?

No, the word order stays exactly the same: Aber die Sache ist wichtig. Coordinating conjunctions like aber, und, oder, and denn take up 'Position 0'. That means they do not count towards the sentence's word order slots, so the subject (die Sache) stays in Position 1 and the verb (ist) stays firmly in Position 2.

How do I pronounce the -ig at the end of wichtig?

In standard German, the -ig ending is pronounced like a soft 'ich' sound, similar to the 'h' in 'huge', rather than a hard 'g'. However, depending on the region, you might also hear native speakers pronounce it with an 'ik' sound.