Incorrect spelling, explanation: the spelling rule says that when a base form of a verb ends in a consonant that is preceded by one vowel, we need to double this consonant while adding the -ing ending. Therefore, the -ing form of the verb run is running. Some English users forget about it and spell the word as runing, which is wrong.

Correct spelling, explanation: the word running entered English from Germanic languages in the times of Old English. Those days, however, it looked completely different than today as it had the forms rinnan or irnan. It was in the 16th century when the -u letter appeared in the word. The base form of running is to run.

Definition of running:
1. noun – using your feet to move quickly;
I want to take up running to lose some weight before summer.
2. noun – being responsible for something, controlling something;
I’ve been running this company for two years.
3. adjective – happening several times;
He’s been late for school three days running.

Expressions with running:
Some typical expressions include: running away, be running short of something, be running scared;
Running away from your problems won’t solve them.
We could stay longer at this beautiful place, but we’re running short of money.
Every time she sees a spider she is running scared.