Tone
Tone is expressed in the wording you choose to convey a particular piece of information. It’s governed by voice, but while voice is consistent across all situations, tone is also influenced by the subject matter.
For example, an inclusive, conversational tone should be used in general copy, but a more formal tone should be taken for serious matters and errors.
When you’re writing, consider the reader’s state of mind. Are they happy to have finished creating a link URL? Are they anxious about seeing an error message? Once you have an idea of their emotional state, you can set the appropriate tone.