When you have taken damage in the past turn, you can gain a +1 to your strength ability score till your next turn(to a maximum of +1). You can do this twice per short rest.

Halfings have no quarrel with anyone and as such they are able to converse with people of all races and backgrounds with ease.

You gain advantage in persuasion rolls

The small size combined with nimbleness of a halfling allows halfling to simply slip pass their foes

You can move through the space of any creature that is of a size larger than yours.

When you roll a 1 on a D20, you can re-roll it. You must use the new roll.

Half-Orcs are able to stay at the brink of death when they endure crippling damage. 

When you drop below 0 hit points, you come back at 1 hitpoint instead. You can only do so once after taking a long rest.

Halflings have a strange resistance to any sorts of magic that attempt to influence their mind

You gain advantage on saving throws against frightened, charm, corruption or curse effects of any sorts(DM interpretation). 

Halflings are extremely small, allowing them to hide almost anywhere

You can attempt to hide anywhere near objects that are smaller than you 

Those around halflings tend to be in good mood and hard to become under a hostile influence

Allies within 15 feet of you can add 2 to a saving throw against being charmed or frightened.