Summoning is a crucial aspect in the game of Yu-Gi-Oh.
In this article i will detail several types of summons:
-Normal Summon
-Tribute Summon
-Flip Summon
-Special Summon
-Fusion Summon
-Ritual Summon
-Synchro Summon
1 || Normal Summons:
A Normal Summon can occur once per turn. A Set is also considered a Normal Summon. Only monsters in your hand of level 4 or lower can be summoned without tribute via a Normal Summon unless effects state otherwise (such as "God Beastking Barbaros"). One important thing to note is that Tribute Summons ARE considered Normal Summons. So, our next category..
2 || Tribute Summon
Monsters levels 5+ cannot be Normal Summoned except by Tribute Summon (unless effects state otherwise, like "God Beastking Barbaros" and "Majestic Mech - Ohka"). A Tribute Summon occurs when a player tributes monster (s) from their side of the field (or their opponents in the case of "Soul Exchange") to summon a monster from their hand. Different levels of monsters require different amounts of tributes. 5-6 stars = 1 tribute, 7+ = 2 tributes. Monsters of levels 5+ still need tributes in order to be set (unless effects state otherwise), so this is known as a "Tribute Set".
Side Note: Tributing for a tribute summon isn't a cost (and has no Spell Speed). You can't chain to the tributing of a monster for a tribute summon, but you can chain to the summon.
3 || Flip Summon
Flip Summons occur when a face-down Defense position monster is switched into face-up attack position. This does not count as your only Normal Summon for the turn, you can flip summon as many times as are possible (as long as there are appropriate monsters to Flip Summon, monsters that weren't set or Summoned that turn, or didn't already change their position). Obviously, when a monster is Flip Summoned, the monster's Flip Effect will activate. Certain monsters like Stealth Bird have effects that activate when Flip summoned. These types of effects won't activate when flipped due to SORL or a battle in which Stealth Bird is flipped up.
4 || Special Summon
Special Summons occur as a result of card effects and don't take up your Normal Summon for the turn. Monsters can generally be Special Summoned in face up Atk or Def position, but in some scenarios like "The Shallow Grave" and "Apprentice Magician" they can be Special Summoned face-down. There are different types of special Summons. There are inherent special summons and non-inherent special summons. Inherent special summons can be negated by Solemn and Raiou. These summons occur as a result of the summoned card's effect ("Cyber Dragon"'s effect to Special Summon "Cyber Dragon", or "Dark Armed Dragon"). The other type of Special Summon not negatable by Solemn and Raiou include monsters Special Summoned by another monster's effect (Dark Creator's effect, Mystic Tomato / other recruiters' effects). Other Special Summons include Fusion, Ritual, and Synchro Summons.
5 || Fusion, Ritual, and Synchro Summons
Fusion Summons occur when a monster is Special Summoned from the fusion deck using a card that states the monster summoned will be summoned via Fusion Summon (Polymerization). As an example, using Polymerization, you send the materials from your hand / field to grave then summon the fusion monster!
Side Note: If a monster wasn't special summoned by an effect explicitly stating the summon was a Fusion Summon, it cannot be Special Summoned from the grave or rfp zone.
Ritual Summons.. occur due to the effects of ritual spell cards, which normally require tributed monsters from your hand or field equal to ("End of the World") or over (most other Ritual Spells) the level of the ritual monster you're attempting to summon. Similar to Fusion Monsters, ritual monsters can only be revived if they were properly ritual summoned before.
Synchro Summons occur when you send a Tuner monsters and another monster on your side of the field to the grave to Synchro Summon a Synchro Monster who's level is equal to the combined level of the two monsters used in the Synchro Summon. This is also treated as a Special Summon, and can still occur if Macro and D-Fissure are in play (reaching the Graveyard isn't necessary, as it's not specified). Similar to Fusion and Ritual Monsters Syncrhos can only be revived if properly Synchro Summoned (not negated).. And,, Synchros can be negated by raiou, oppression, and solemn.