Field Research tasks can be collected by spinning nearby PokéStops, and they include a wide range of Pokémon-related activities. Gym photo-disc spins do not give research tasks.
Research tasks are the same for everyone but change location randomly every day at midnight (your local time), which means that you can only collect one specific task from each PokéStop, each day.
You can hold up to three unclaimed field research tasks at a time, plus up to 100 stacked encounter task that you’ve already claimed. If you get a task you don’t like, you’re not forced to do it; you can just trash it by pressing the little bin icon in its top right corner. If you trash a task, but later decide you want to do it, you can go back to that Pokéstop and pick it up again (provided you do so before midnight else it will have changed).
Completion of your first Field Research task each day rewards you with a Research Stamp. You will be able to complete multiple Field Research tasks per day but no matter how many tasks you complete, you can collect only 1 stamp per day. Unlike daily catch/spin streaks however (which require you to catch a Pokémon / spin a PokéStop for 7 days in a row), Research Stamp progression will not reset even if you miss a day.
Each task you complete will reward you with either items, stardust or a Pokémon encounter. Generally speaking, the more challenging a task, the better the reward.
Once you have been rewarded with your seventh stamp, you will be able to claim a Research Breakthrough. Research Breakthroughs reward you with items, stardust and XP, but the main reward is that you will encounter an exclusive Pokémon. These can be Pokémon with a legacy/exclusive move, previously unreleased Pokémon, or (usually) a Legendary Pokémon which has previously been featured in Raid Battles!
There will be preconditions to some specific quests. This means that some of the quests will only be unlocked after you reach a particular level/medal in the game.
The pool of Field Research tasks gets tweaked on the 1st of every month, based on a certain theme or Pokémon type. We at Go Hub always endeavour to inform you of the new tasks as quickly as possible so please check our news round-up at the start of each month for a full list of the current Field Research tasks.