Internet slang used to express laughter, similar to 'LOL' or 'haha' in English. Often used at the end of sentences or as a standalone reaction. The reading わらい is also possible but less common.
See also: 笑い
That video is too funny lol
I was late again today haha
笑う is the ordinary verb 'to laugh', whereas 笑 alone is a net-slang interjection used like 'lol', not a conjugated verb form.
Most common written form in internet slang; read as わら.
Abbreviation using the first letter of 笑 (wara); multiple ｗ can be used for emphasis.
Rarely used kanji form; originally means 'straw' but used here as ateji for わら.
Derived from the kanji 笑 (laugh), used as internet slang to indicate laughter. The reading わら comes from the kun'yomi of 笑う (warau).