Here is a brief summary of the common information I dug up about visiting prisoners. Keep in mind that jails/state prisons/federal prisons all operate differently.
Before someone can visit a prisoner, they have to be on that person’s approved visitor list. The inmate is responsible for maintaining the list.
The next step in visiting a prisoner is to make an appointment. This is an issue in itself as the phone line is only open for a few hours a day. Many people have to call over and over again because the line is busy. When they do get through, the next available timeslot could still be weeks out, and even then it’s not guaranteed. The prison could be on lock down that day, or the inmate may have had visiting priviledges revoked for behavioral issues. It is up to the visitor to call that day and confirm the visit. Also, the inmate could be moved to a during the interum, which apparently happens quite a bit.
On the visitation day, the visitor must fill out paper work, show identification, and go through a security check much like at an airport. Many prisons don’t allow shoes, jackets, or sweatshirts to be worn inside. Bags and purses are checked at the door. There are different rules on what can be brought inside. Some prisons allow items like photos but do not allow anything to be left with the prisoner. Many allow a certain dollar amount of quarters for vending machines that are inside the visiting room, or they may provide a vending machine debit card. There are even rules on what you can wear (clothing, jewelry, etc.).
If the visit is a contact visit, the visitor is assigned a table and waits for the inmate to be brought into the room. Most of the rules I found stated that brief contact (a hug, a kiss) was allowed at the beginning and end of the visit. Hand holding is allowed at some institutions as long as it is in plain sight. Some also allow small children to be held during the entire visit. Visits can last anywhere from 20 minutes to a few hours, depending on the prison and the security risk/earned privledges of the inmate.