A solar eclipse happens when the moon passes between Earth and the sun, casting a shadow on part of Earth's surface. Which type you see depends on how precisely aligned the eclipse is and how far the moon happens to be from Earth at the time (its orbit isn't a perfect circle, so its apparent size in the sky varies slightly month to month).
Total solar eclipse
The moon completely covers the sun's disk, as seen from a narrow path on Earth called the path of totality. Within that path, the sky darkens like twilight for a few minutes, and the sun's outer atmosphere — the corona — becomes visible as a pale ring. Outside the path, only a partial eclipse is visible.
Annular solar eclipse
The moon is aligned with the sun but is far enough from Earth in its orbit that it appears too small to fully cover the sun's disk. The result is a "ring of fire" — a bright ring of sunlight visible around the dark disk of the moon at the peak of the eclipse.
Partial solar eclipse
The moon covers only part of the sun's disk, either because the viewer is outside the path of totality/annularity during a total or annular eclipse, or because the alignment itself is only partial. Most people who experience a "solar eclipse" without traveling to a specific path are seeing a partial eclipse.
Viewing safety
Never look directly at the sun during any phase of a partial or annular eclipse, or during the partial phases of a total eclipse, without certified eclipse glasses (ISO 12312-2) — ordinary sunglasses are not sufficient and can allow permanent eye damage. The only time it's safe to look with the naked eye is during the brief total phase of a total eclipse, when the sun's disk is fully covered.
See upcoming solar eclipse dates and where they'll be visible on the homepage or the full eclipse calendar.