I have received an email with this subject "Invitation to visit day" and below is the content. I was wondering if this is an acceptance or not.
Good luck to all of you.
Congratulations! The admission committee of the ... Department has just nominated you for admission to our PhD program and for receiving a financial aid offer. The administrative procedures of our university will slightly delay formal notification of the details of admission and the financial aid offer, but you will be receiving those shortly.
In the meantime, and on behalf of our department, I would like to invite you to attend our official visit day for prospective graduate students.