Protips for new players (Diablo 3)

This post is aimed at new and returning Diablo 3 players, and contains lots of facts and info about the game and how to play it. Feel free to also drop any other protips in the comment field, and I will include them here in future updates.

- Creating a seasonal hero will unlock the Adventure Mode automatically. You regularly need to beat the Story Mode to unlock this mode.
- Adventure Mode lets you do rifts and bounties.
- Rifts have higher chance of dropping legendary items, and also drop keys for Greater Rifts.
- Greater Rifts is an infinite progression system where you have to beat a rift and the boss within a 15 minute timeframe. Completing this successfully gives you a chance to upgrade legendary gems.
- Bounties award special materials that can be used to craft legendary items and used for recipes at Kanai's Cube.
- Using a Puzzle Ring at Kanai's Cube will open a portal to The Vault - an instance that contains a lot of goblins, an insane amount of gold (especially at lower levels) and a boss that drops at least two legendary items.
- The difficulty system gives you more XP and higher legendary drop chance for each difficulty level.
- The stash is shared across all heroes at the same game mode, for a total of four (normal softcore, normal hardcore, seasonal normal and seasonal hardcore).
- Once you reach max level the XP you gain is awarded towards your Paragon Level. Each new Paragon Level lets you add a point towards a stat.
- There is an infinite amount of Paragon Levels, but each level takes more time than the last one. At 800 and up all new levels gives you +5 points to either your main offensive stat, or +5 towards Vitality.
- Seasons comes with a Season Journey. These are kind of like achievements that you can complete, and gives you rewards such as a 6 piece set for your hero, as well as vanity items such as portrait frames, pets, pennants etc.
- There are still items in the game that has yet to be found by a player, such as the Fallen Pennant.
- Pressing F1 on your keyboard opens the cosmetic tab that allows you to equip pets, pennants, portrait frames and wings.
- Once you have reach level 70 you should work towards getting a set of Legendary Items. The set bonuses are extremely powerful, and are mandatory to be able to clear high level Greater Rifts.
- Each class set also has a Set Dungeon. Completing all of this with any class awards a set of vanity wings that can be equipped.
- There is not a lot of online play at lower levels, but once you hit max level, there will always be a lot of other players in the public games.
- Save at least one of your nice Legendary Items for Kanai's Cube. These can be used as a passive bonus once the cube has been unlocked.
- Always do the bonus act when doing a bounty, as a new act will be the bonus act once the current bonus act has been completed. The bonus act awards twice the amount of caches / loot.
- Gems can be upgraded for more powerful gems at the jeweler. Each new tier of gems require 3 of the previous tier.
- Greater Rift bosses drop Legendary Gems which can be slotted onto the two rings and the amulet. These are very powerful, and can be upgraded by running Greater Rifts.
- You can get plans for your Blacksmith from doing bounties, and from Odious Collector (a goblin type).
- Vanity pets pick up gold automatically. They can be gotten from menagerist goblin, or from other drops (such as the Liv Moore pet).
- If you find a weapon with a socket at low level, use a ruby or emerald gem in it to increase your damage by a lot! 
- Hover over your friend tab in the bottom right corner, and you can open the community tab. Here you can join different communities, such as vanity items hunters, achievement hunters, greater rift groups etc.