Mardi Gras, also known as Fat Tuesday, is an annual carnival celebration that takes place in various cities around the world, with the most famous and elaborate celebrations occurring in New Orleans, Louisiana, United States, and Rio de Janeiro, Brazil. The term "Mardi Gras" is French for "Fat Tuesday," and the event marks the culmination of the Carnival season, which begins on Epiphany, also known as Twelfth Night or Three Kings' Day.

Mardi Gras is a time of revelry, feasting, and merriment before the beginning of Lent, a Christian period of fasting and penance leading up to Easter. The exact date of Mardi Gras varies each year, as it is determined by the date of Easter, which itself depends on the lunar calendar.

The celebration typically involves colorful parades, masked balls, music, dancing, and extravagant costumes. Floats decorated with elaborate designs and themes pass through the streets, accompanied by costumed performers and musicians. People wearing masks and vibrant outfits throw beads, coins, and trinkets to the crowd, creating a festive and lively atmosphere.

In New Orleans, Mardi Gras is a deeply ingrained cultural event that has been celebrated for centuries. Various "krewes," social organizations or groups, organize and sponsor the parades and balls, each with its own unique theme and tradition. The celebration also includes king cakes, a sweet pastry traditionally served during the Carnival season.

In Rio de Janeiro, Brazil, the Carnival celebrations are world-famous, attracting millions of visitors each year. The main highlight is the samba parades, where elaborate samba schools compete with impressive floats, dazzling costumes, and synchronized dancing in a massive stadium known as the Sambadrome.

Mardi Gras is known for its vibrant and inclusive spirit, welcoming people of all backgrounds and cultures to participate in the festivities. It is a time of joy, unity, and celebration, bringing communities together to revel in the exuberance of the season before the solemnity of Lent begins.

Over the years, Mardi Gras has evolved and been influenced by various cultures and regions, resulting in unique and diverse celebrations worldwide. The event is a significant tourism draw and plays an essential role in preserving cultural heritage and fostering a sense of community and identity among its participants.