The Gili Islands are three small very small but popular islands with turquoise waters and white sandy beaches. They're actually part of Lombok, the island next to Bali, and gili means island in Sasak, the local language in Lombok.
The 3 islands are Gili Trawangan (Gili T), Gili Meno and Gili Air. Gili T is the most popular and is considered the "Party Island", while Gili Meno is the "Honeymoon Island" and Gili Air is kind of halfway between the two. Personally, we've only visited Gili T so far, but we'd like to check the others out at some point - apparently the beaches in Gili Meno are the best!
They all have really nice resorts, but also cheaper places to stay, and they're great for scuba diving/free diving, and snorkelling, where it's very easy to see turtles!
One thing you'll notice on the Gilis is there's no dogs and only lots of cats! There's also no scooters or cars on the islands (maybe one or two) and the only way to get around is by bicycle, which is actually kind of nice! (actually another way to get around is by horse, but it seems a bit inhumane).
We can neither confirm nor deny whether this is the place where people go to take mushrooms...
Pro Tip: Lombok is Muslim, and so are the Gilis, so hotels close to the mosque are cheaper presumably due to the early morning call to prayer on the megaphone, which we found out lol.
Pro Pro Tip: It takes a looongg time to get to The Gili Islands (2+ hours) from Bali, and they're a bit overrated! It's cool to see turtles, but other than that there are a lot of other cooler places in Bali that aren't so far away - in our opinion. So firstly, don't go for more than 2-3 days (unless you're doing a diving course or something which is probably very fun), or don't go at all and check out the Nusa Islands instead!
Super Pro Tip: take enough cash as ATMs are limited.