have: infinitive had: past simple had: past participle

both "have had" and "had had" are in perfect form / construction (i.e. present perfect and past perfect resspectively). the present perfect tense is used when we want to connect the present with the past actions or experiences. "I have had a terrible evening with my peers." we use the Past Perfect to show that something started in the past and continued up until another action in the past. "I had had a word with my boss about my promotion before I left the office." also, "have had" and "had had" can be contracted as 've had = "I've had" "we've had" 'd had = "I'd had" "they'd had" :)

We use HAVE for present simple( i have a car means; right now i have a car) We use HAD for past simple( i had a car means ,i no longer have a car) Also HAD is past simple and past participle for HAVE

Example: I have a house. I have had a holiday house but I sold it.