Easy

"Your foes cower and fall before your unstoppable onslaught, yet final victory will leave you wanting more."

- Description from Halo: Combat Evolved, Halo 2, Halo: Combat Evolved Anniversary, and Halo: The Master Chief Collection.

"Laugh as helpless victims flee in terror from their inevitable slaughter. The game basically plays itself."

- Description from Halo 3 and Halo 3: ODST.

"Laugh as helpless victims flee in terror from their inevitable slaughter. Achievements cannot be unlocked on this difficulty."

- Description from Halo: Reach.

"Laugh as helpless victims flee in terror from their inevitable slaughter."

- Description from Halo 4.

"Casually operate with impunity and slaughter foes with ease. Recommended for players new to Halo."

- Description from Halo 5: Guardians

"Cut through your foes with ease and revel in your unstoppable onslaught. Recommended for players new to Halo Wars 2."

- Description from Halo Wars 2

Easy is the least challenging difficulty setting on Halo: Combat Evolved, 2, 3, 4, Halo 3: ODST, Halo Wars, Halo: Reach, Halo 5: Guardians, and Halo Wars 2. The enemies are few, target inaccurately, and are overall far weaker than on higher difficulty levels. Many players use it to learn the story. After they accomplish it on Easy, they will often play again on harder difficulties.

Summary
The icon for the Easy difficulty setting is represented with a shield that has the Marathon logo encrusted into the center. This is for people just beginning to enter the Halo Universe and the first person shooter genre in general.

Notable differences on this difficulty include:
 * Increased shield and health strength.
 * Reduced health and shield levels for enemies. Most enemies die from a single melee.
 * Elites, Brutes, and/or Promethean Knights are less common, and there are very few Major Elites, Brute Captains, Soldier Snipers, and/or Knight Commanders; Minor Elites, Brute Minors, standard Promethean Soldiers, and/or normal Knights are almost exclusively seen.
 * In Halo 5: Guardians, Promethean Crawlers' built-in Boltshots almost never exhibit homing behavior.
 * Notable reduction in enemy intelligence. Enemies are far more reckless and easy to kill.
 * Marines and other allies are tougher, more accurate, and deal more damage.
 * Meta-point score is reduced to 25% of that of Normal.

Trivia

 * In mainline Halo games from Halo 3 onwards, including Halo 3: ODST, the game will keep track of the highest difficulty you have finished the Campaign on, in both Solo and Co-op.
 * Most of the achievements in the Halo series do not unlock when played on Easy, as most need to be on Normal or higher, although there are exceptions. In addition, no skulls will appear in Halo 3 when played on Easy difficulty except for the Mythic skull for unknown reasons; however, the achievement for finding it will not be earned even if collected.
 * Developers have referred to Easy in Halo: CE as "grandma mode", according to the official guidebook.
 * 343 Guilty Spark will suggest that the player switch to "Easy" if the player starts attacking allies in Halo 3 with the IWHBYD Skull activated.
 * In the beginning of each of the Halo games, there is a look inversion test on Easy and Normal to set your preferred view inversion setting, whilst on Heroic and Legendary, it will skipped based on the assumption that you will already be familiar with them.
 * The look inversion tests are skipped entirely from Halo 4 onwards.
 * Commendations and Challenges will not advance on the Easy difficulty.