Z with stroke

Ƶ (minuscule: ƶ) is a letter of the Latin alphabet, derived from Z with the addition of a stroke.

Uses

It was used in the Jaŋalif alphabet (as a part of Uniform Turkic Alphabet) for the Tatar language in the first half of the 20th century to represent a voiced postalveolar fricative [ʒ], now written j. It was also used in the 1992 Latin Chechen spelling as voiced postalveolar fricative [ʒ]. It was also used a 1931 variant of the Karelian alphabet for the Tver dialect.

As handwriting

Italians often use it for the [dz] sound in the hand-writing, while the normal Z is used for the [ts] sound. In Polish, the character Ƶ is used as an allographic variant of the letter Ż. Germans and Spaniards often use this sign in the hand-writing as the letter Z, as do others.

As currency

Ƶ was sometimes used instead of Z to represent the zaire, a former currency of the Democratic Republic of Congo.

Also, the popular British TV show Doctor Who uses ƶ as the symbol for the unit of money, Galactic Credits.

In science

Ƶ is also used by mathematicians, scientists, and engineers as a variant of Z in hand-written equations, so as not to confuse the symbol with the numeral 2.

Uses on computers

The Unicode of uppercase Ƶ is 01B5, while the lowercase ƶ is 01B6.