The present perfect tense is used to describe actions or situations that have occurred at some point in the past but are relevant to or have an impact on the present. It is formed using the auxiliary verb "have" (or "has" for he, she, it) followed by the past participle of the main verb.
### Structure
- **Affirmative:** Subject + have/has + past participle
Example: "I have visited Paris."
- **Negative:** Subject + have/has + not + past


