The past tense is used for things that have already happened. He was sticky. The present tense is used when something is happening now or when something happens regularly. He is sticky.

The perfect tense is used to express things that have happened in the past in general. It is the most commonly used past tense in German. It is used in letters, emails and spoken German.

For example, the tense may change between the methods section and the discussion section. The abstract is usually in the past tense due to it showing what has already been studied. Example: “This ...