Maria
Maria explained in an easy to understand way:
Imagine you're in your kitchen, and you've accidentally overcooked a pot of soup, causing it to bubble over and spread across your stovetop, leaving a flat, dark stain. This bubbling and spreading is similar to how ancient volcanic activity on the Moon caused molten lava to flow across its surface, eventually cooling and creating large, dark, flat regions known as maria. Just like the soup spreading on your stovetop, the lava on the Moon spread out and solidified, leaving behind these expansive, dark areas that are easily noticeable from Earth.
Practice Version
Maria: Dark, flat regions on the Moon made of ancient lava flows. Maria are large, basaltic plains formed by volcanic eruptions on the Moon's surface.