A hitbox is a term used in fighting games that refers to the attacking area of an offensive action.
Priority works differently in Street Fighter than other games as it doesn't have mechanics such as the "Port Priority" system the Super Smash Bros. series has. Priority can mean different definitions. Generally when speaking of strikes, the general meaning refers to the startup frame data, hurtbox extension of the attack, and the reach of the attack. Anti Air attacks tend to give very little vertical hurtbox extension for example. This is to ensure that they can work to task. It should be noted that when not taking invincibility into account, low priority attacks such as Rufus's 16 frame startup can beat Cammy's 3-frame jab with the right timing.
Street Fighter V introduced a true priority system. Within this system (assuming both attacks active hitbox activate at the same frame) a medium will defeat a light attack, and a hard attack will defeat a medium. Attacks of lesser strength CAN still catch the startup of harder attacks. Interestingly, some command grabs from characters like Rainbow Mika have an odd mechanic that if two players use the same grab the winner is literally determined by if the game is in an odd or even frame.
Invincibility refers to the amount of frames during which a character lacks any "vulnerable" hitboxes/hurtboxes (e.g. the aforementioned Shoryuken), meaning that they cannot be hit.
This is often done in one of two ways depending on the game; hitbox/hurtbox invincibility often refers to hurtboxes either shrinking and/or disappearing in order to completely phase through attacks. Attribute invincibility is when while the hurtbox is still registered, it becomes invincible to specific types of moves within a certain frame without radically shaping itself and/or disappearing (e.g. a move that is completely invulnerable to lows or highs despite their hitboxes contacting the hurtbox during its period of attribute invincibility). An example of specific hitbox invincibility can be seen with Ibuki's EX Neck Breaker in USFIV where it is completely projectile immune but still loses to grabs and strikes or Rose's EX Soul Spiral that is completely immune to strikes and projectiles she can be thrown out of the attack.
Types of hitboxes Edit
Street Fighter in general tends to use three types of hitboxes. Strike, Projectile, and Throw (grab).
Arguably the most common hitbox. Most normal, unique, and a good amount of special attacks tend to be of this hitbox type. Strike hitboxes are used for a multitude of reasons, either single hit attacks, Combo's, or projectile bypass. Every character has access to this type of attack. Interestingly, some thrown items such as Ibuki's Kunai and Rolento's Stinger are classified as strikes rather than projectiles. This comes with the benefit of these attacks being able to stop projectile immune actions but at the price of being able to be knocked away when they themselves make contact with other non grab hitboxes.
Types of strike hitboxes. Edit
High hitting hitboxes refer to attacks that can not be blocked low. Every character in the game has access to this style of hitbox in the form of aerial attacks. Some characters have aerial target combos such as Ibuki's Target Combo 1 that despite using 2 hits in the air, the second can be blocked low, or others such as Chun-Li has a double hitting hard punch aerial attack that the whole sequence has to be blocked high. Most special and unique attacks such as Cannon Spike and Falcon Kick can actually be blocked low despite being aerial attacks. Some special attacks such as Hien can only be blocked high, despite starting from the ground.
A good amount (but not all) Street Fighter characters have access to Overhead attacks. These attacks can not be blocked low. These attacks were created since the most common blocking position is down-back.
Overheads vary in usage, some are simple one hits, others are slow but avoid attacks during start up, others are used for full combos. Characters that do not have access to overheads tend to either have very far reaching Command Grabs or Walk Speed to help them close distances.
All characters also have access to these style of attacks. Low attacks are mostly crouching kicks (most notably Sweep). Some special attacks such as Tsumuji can also have a sweep-like effect that hits low. Long reaching low attacks are a great tool in footsies, as it can help prevent a free escape for fast walk speed characters, especially if the low is special cancel able, or prevent slower walk speed characters from coming in. Users should be warned that some normals or Unique Attacks such as Bonshogeri are made to bypass and punish low attacks specifically.
While not common, some characters (especially in cross over games) have standing attacks that still hit low. A notable example would be Asuka Kazama's forward MK in Street Fighter X Tekken. These can bypass some rules for lows, such as standing low attacks bypassing the immunity Launchers have for typical crouching low attacks.
Unlike strikes, not every character has access to projectile hitboxes. Projectiles usually are fireball style attacks that are shot. The Hadouken and Tiger Shot were the first of this type, as they both debuted in the original Street Fighter.
Projectile users tend to need to be aware of their opponent's moveset, as projectile invincibility is the most common style of invincibility in game. Fragile Speedster style characters tend to have many ways of bypassing projectiles with Unique Attacks or Special Attacks. Some projectile users themselves tend to beat theoretically better users due to their moveset, such as Chun-Li making Sagat using Tiger Shot a risk as she can punish his projectile at any range of the screen. Other characters such as Hugo's Giant Palm Bomber will actually nullify 1 hit projectiles when they make contact. When two projectiles meet they tend to cancel each other out. In modern games projectiles have "points" where each regular projectile has 1 point and when they meet other projectile they disappear. EX projectiles tend to have two "points" and go through 1 point projectiles after they lose one hit point themselves (meaning instead of hitting twice they will hit once). Super and Ultra fireballs tend to have even more points than EX.
Not all projectiles have screen travel. Some attacks like Ibuki's Tenrai are classified as projectiles. The general rule is if there is any presence of KI that fits the character's motifs the attack is classified as a projectile. Yun's Kobokushi is also a projectile hitbox despite how non-obvious it is. Another indicator for projectile hitboxes could be if the visual effect when the attack connects isn't the usual strike hitbox hit or block effect.
GrabEditGrab hitboxes are the final main type of hitbox in Street Fighter. They bypass blocks. Every character in Street Fighter has access to at least one grab style attack, these are called "Normal Grabs".
Command Grabs are a style of grab that a certain sequence needs to be inputted to come out. They tend to do more damage and have more range than regular throws (that characters with Command Grabs also have) but they have much higher recovery. Some characters such as E. Honda have command grabs as an added bonus of their attacks while some like Zangief revolve around command grabs.
Throws bypass Super Armor and the rare Hyper Armor, unless the character that possesses the attributes are unthrowable. These situations tend to be more common in crossover games with boss characters like Onslaught in Marvel vs Capcom or some attacks from Bob Richards in Street Fighter X Tekken.
Throws usually also are uninterruptible when connecting. Meaning that once a throw successfully connects the sequence can not be stopped, from either a projectile or even a partner in games that allow the feature. This can make throws a good punish option such as punishing a point blank Yoga Catastrophe by grabbing Dhalsim after the cinematic startup or punishing game specific tactics such as a Shoryuken Switch Cancel with an Air Throw in Street Fighter X Tekken.
Airborne Frames make characters unthrowable also.Every character in the gamer has access to airborne frames with their Jump. Some attacks such as Ibuki's Hammer Kick have airborne frames built into the attack and can punish throw whiff animations. There also exist Air Throws that work in the inverse situation, they only work against airborne opponents and whiff against grounded ones.
Unique properties Edit
Some attacks do not follow the standard rules of hitboxes and can have a mixture of attributes of each attack type
Ibuki's Raida is is one of the oddest attacks in Street Fighter history. It's hitbox is a strike but everything else that proceeds it is treated as a grab and active frames tend to catch attacks the same way a command grab would grab extended hurtboxes. However Ibuki's Raida is actually classified as a strike in all of it's appearances, this means that it can also catch airborne attacks and extended ungrounded hurtboxes like Dhalsim's extended limb attacks. Furthermore it's SFV incarnation also keeps the unique property of throw and command grab attacks where the opponent can not back roll. Meaning Ibuki doesn't have to take that into account when ending her combos with Raida.
Unlike every other Ultra Combo projectile Meido Gohado uses a strike hitbox in conjunction with the projectile in order to check distance. The hitbox projectile is used to check if it was a point blank hit and if it connects Oni's animation cinematic will play instead. If it doesn't connect Oni proceeds to use his ultra like any other projectile such as Metsu Hadoken. This means that attacks such as Neck Breaker that beats every projectile has to be used at a specific distance because at point blank the ultra will still hit.
Ibuki's Kunai and Rolento's Stinger Edit
As mentioned before these throwable weapons are actually classified as strikes rather than projectiles. They do not lose to projectile immune attacks but actually have a hurtbox of their own and if they come in contact with a hitbox (aside from grab) the weapon will be knocked away, similarly to when two projectiles clash with each other.
In Street Fighter X Tekken despite these being airborne objects they bypass the jump in immune check of characters like Law's anti air.
Abigail's Diagonal Jumping Hard Kick. Edit
Abigail's jumping hard kick, despite being classified as a high strike attack (meaning it bypasses crouching guard) actually doesn't hit crouching characters.
Projectile Unique Attacks Edit
Some Unique Attacks such as Rufus's Fragrance Palm is actually classified as a projectile in some appearances and nullifies other projectiles on contact of both hitboxes. Two projectile physical hitboxes clashing gives the same effects and follows the same "hitpoint" style of thrown projectiles when they make contact.
In Street Fighter X Tekken Ibuki's Agemen made her upper body invincible. Meaning no kind of hitbox could hit her waist up. This is often confused but is different to the jump in immune property of characters like Law and Asuka with their own anti air, that only makes them invincible to airborne hitboxes rather than all kinds of attacks. This can make Ibuki avoid some attacks such as Marduk's spinning backfist or high Tiger Shots with Agemen.
While some Command Grabs such as Hugo's Ultra Throw or Abigail's Abigail Smash can be comboed out of. Gouken's back throw Amaroishi is the only regular throw (without enhancements) that can be fully comboed out of. The most popular option is Shin Shoryuken (when available).