Giardia is a common intestinal parasite that causes giardiasis, a diarrheal ailment that affects people all over the world. Giardia duodenalis and Giardia lamblia are tiny organisms that live mostly in the small intestines of humans and other mammals. Ingestion of contaminated food or drink, generally beginning from fecal matter containing Giardia cysts, causes transmission. This can occur in a variety of contexts, including poorly treated water supplies, recreational aquatic areas, or contact with infected individuals. When the cysts are consumed, they pass through the stomach and into the small intestine, where they convert into active trophozoites, the infectious form. These trophozoites cling to the intestinal lining, hinder nutrient absorption, and promote inflammation, resulting in diarrhea, abdominal cramps, bloating, nausea, and exhaustion. Notably, some Giardia-infected persons may remain asymptomatic carriers while still shedding cysts in their feces, potentially functioning as sources of infection. Stool sample analysis to detect Giardia cysts or trophozoites is frequently used in diagnosis. Antibiotics such as metronidazole or tinidazole are commonly used in treatment to efficiently remove the parasite. However, some Giardia strains have developed resistance to specific drugs, necessitating alternate treatment methods. Prevention techniques include practicing excellent hygiene, such as handwashing with soap and water after using the restroom or changing diapers, and before handling food. In places with questionable cleanliness, boiling or filtering water before drinking can also minimize the risk of infection. Avoiding touch with possibly contaminated surfaces or feces from diseased animals can also aid in the prevention of transmission. Giardia's impact extends beyond physical symptoms, as persistent infections can result in malnutrition, weight loss, and stunted growth, especially in children. Furthermore, visitors to areas with poor sanitation should exercise caution in order to limit their exposure. To reduce the spread of Giardia infections, public health efforts attempt to enhance sanitation, water quality, and hygiene education. Understanding the parasite infection's lifecycle, transmission routes, and effective prevention strategies are critical for controlling it and minimizing its global public health burden.