Gingivitis is a common and mild form of gum disease (periodontal disease) that causes irritation, redness. and swelling of the gingiva, the part of the gum around the base of the teeth.

Insight:

Gingivitis can lead to a much more serious gum disease, called periodontitis, and tooth loss.
The most common cause of gingivitis is poor oral hygiene.
Symptoms include swollen or puffy gums, dusky red and dark red gums, gums that bleed easily, bad breath, receding, and tender gums.
Risk factors include poor nutrition, dental restoration, genetics, dry mouth, and older age.
Prevention may include good oral hygiene, regular dental visits, and good health practices.

Sources:

Gingivitis - Diagnosis and treatment - Mayo Clinic

gingivitis images - Google Search