what exactly is an Internal hernia?

I was wondering what the difference between a hernia and an internia is?  Many of you know I went through major complications over the past 7 months and as I read one of the reports from the hospital, it said that not only did I have a bowel obstruction but I had an internal hernia.  Just curious  - then that let to even more complications.

 Not positive but when I had my first WLS it was done lap and I was warned about a complcation where there were holes left in the mesentery where the intestines can slip through.  I was told that some surgeons were sewing the holes closed to prevent this.

I was in the ER for the first time this week. I have absolutely no complications since my had a horrible hearburn like symptom in the middle of my upper back that got worse.  I honestly thought, after reading this site, I had gall bladder issues.  When I got there, they were concerned about the internal hernia which they said could be life threatening.  It is when the pouch and the intestin fold under....whatever that means.  Turns out after a CT scan and blood work, they didn't find anything but started me on prevacid, and nausia/cramping meds.  I pain is still there, so I am going to make it through the weekend and see my surgery.