A backpack is a survival kit for the hiker. What you pack and what to leave is a very personal decision and is a mix of the hike and the personality of the hiker.
Packing the right stuff is very important. At the end of the trip it is likely that the main cause of feeling that your trek was a success or not will be based (partly) on what’s in your backpack.
Nobody like a heavy backpack. A heavy backpack weights down the hiker. You can’t cover as much ground. Injuries go up with the weight of the pack.
One good rule of thumb is to have your backpack weigh no more than a quarter of your bodyweight. This gives you the chance to balance utility vs. endurance for the hike ahead. Even with only 25% of body weight you can still pack a lot of equipment.
Of course, lighter is better. But how? One option is to buy lightweight equipment. Two potential issues with this are cost and quality. The best lightweight equipment is expensive and cheaper equipment will often break and be ineffective. Of course, you could always pack less stuff.
Backpacking gear is a big industry and you can find kits and package deals if you are a beginning hiker. In addition to basic camping equipment, many kits and pieces come in durable plastic and aluminum alloys that help reduce the overall load.
One word of advice - don’t buy a fancy backpacking stove. Go old school and use a ‘beverage can stove’.
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