Slice of Life

In anime and manga, slice of life, abbreviated SoL, is a genre where the series focus on the daily, mundane lives of the characters. What this means exactly depends on what those characters are and what in the world are they doing daily.

Often, a slice of life series will feature a tranquil atmosphere, since most characters will be friends, or classmates, or colleagues working for the same company, and all they'll do is just do mundane stuff like joke around, study for the finals, and prank each other.

The term for "slice of life" in Japanese would be nichijoukei 日常系, which translates to "daily life-class." See the -kei ～系 suffix for reference.

Funnily enough, the manga and anime Nichijou 日常, "Daily Lives," is one such slice of life, nichijoukei, series. It's also a comedy, or rather, joke, "gag," gyagu ギャグ, series, and a CGDCT series.