1.9 - The Combat Update

1.9 (also referred to as The Combat Update) was an update for Minecraft, released on February 29, 2016.

Java Edition version history
◄ 1.8 • 1.9 • 1.10 ►

Additions

New "tipped" arrows, which apply potion or status effects.
New "spectral" arrows that create a glowing outline around the target, making them visible to the attacker through any blocks. (JE only)
Axes do more damage, but swings slower. (JE only.)
Weapon damage is now dependent on an attack strength bar that is depleted when a player swings, and regenerates over time. The more the bar is filled, the more damage a player will do.
Added shields, which block attacks when a player right clicks. Axes have a chance of disabling the shield for 5 seconds(JE only). A player can combine a banner and a shield to make the shield have the banner's design and colors on it.
New "sweep attack" when attacking with a sword while crouching or standing. It can knockback multiple enemies at once.(JE only)
Dual-wielding. If a player puts an item in the off-hand slot, they can use it by right clicking, and typing F (that is the default button) switches the main-hand and off-hand items.(JE only)
Mobs now give off particles when hit that show how much damage was done to them.
New items called Lingering Potions. They are thrown like splash potions, but create a cloud affecting anyone who walks through it.

There is a new Igloo structure in Snow Plains.
A new End City and End Ship structures in the outer End.
New Chorus Plant Trees.
Now up to 128 strongholds generate per world.
New End Gateways spawn after killing the Ender Dragon. A player must use an Ender Pearl to go through it.
The inner End is now more like the Console Edition.

Purpur Blocks in the End.
Frosted Ice
Grass Path, created by right clicking a grass block with a shovel.
Decorative Dragon Head blocks in the End.
New Structure Blocks that are used by developers and only placed using /setblock command.
Chorus Plants able to give a food item (Chorus Fruit)
Chorus Flower able to grow Chorus Plants.
End Rods in the End to light up end cities .

Elytra, which are wings that can be used to glide and are obtained in the End.
A new plant called Beetroot, which can be grown with Beetroot Seeds, or made into Beetroot Soup.
Ender Crystals (which spawn naturally on the obsidian towers in the End) can now be crafted and can be used to re-summon the Ender Dragon.

There are new mobs called Shulkers, new mobs that spawn in End Cities.
There are now Skeleton Trap Horses, which is a Skeleton on top of a Skeleton Horse.

If a player shears a Snow Golem, its pumpkin will come off of its head.
Wearing a certain mob head will allow a player to get a bit closer to that type of mob before it starts chasing them.
Now Blaze Powder is needed to operate a Brewing Stand.
You can no longer possible to craft Enchanted Golden Apples, but they may still be found rarely within chests.
Added new enchantment (Frost Walker), which creates solid frost blocks when walking over Water.
Some enchantments have been re-balanced.
New sound effects and sound effect subtitles
Revamped Ender Dragon fight to be harder and more challenging.
Golden apples and armor have been re-balanced.

Pigs can now be bred with Potatoes, Carrots, and Beetroot. Before 1.9, they could only be bred with carrots.
Chickens can now be bred with any type of Seeds, including Nether Wart

1.9.1 was released on March 30, 2016 with changes to armor toughness and mob AI, the addition of sounds for Elytra, and fixes for 13 issues.

1.9.2 was released on March 30, 2016, and fixed some bugs – one of which was a major multiplayer bug.

1.9.3 was released on May 10, 2016, and added the /stopsound command, improved the /tp command, and better manages memory.

1.9.4 was released on May 10, 2016, and fixed a few bugs.

A Mojang promotional image for the Combat Update

A Mojang promotional image for the Combat Update