Autoimmune protocol, it’s an elimination diet that seeks to remove common allergens and foods that can trigger an immune response (grains, alcohol, nuts, seeds, nightshade veggies, dairy, seed oils, eggs). After about a month on it you reintroduce foods that have been eliminated one by one, waiting several days between reintroductions to determine if they are causing you problems. This diet has been an amazing transformation for my husband whose reflux, IBS, body aches, sleep apnea, eczema and chronic nasal issues have been dramatically improved by it. It’s a version of really low carb paleo/keto diet.
He is a FOODIE so it was hard at first, but now he is happily following it and doesn’t plan to end it. He has identified several things that trigger him and reintroduced several things successfully. His IBS, interestingly, seems to continue improving and he is now having pretty normal bowel function on a daily basis 90% of the time. That was his worst problem, he was running to the bathroom several times a day. His sister had the same issue and has also cured it with an elimination approach.
For me, keto, which I was on for more than a year before AIP, reduced my knee pain and I had no additional benefit from the AIP that I can tell.
Hopefully this helps. You will see AIP if you do a search in this forum. I believe there are several people who have used it in the context of keto to heal themselves.