Questions & Answers about Το τατουάζ είναι μικρό.
Το is the definite article meaning the.
In this sentence, το goes with τατουάζ to mean the tattoo.
Greek articles change depending on gender, number, and case, so you cannot use just one form for every noun the way you often do in English. Here, το is the neuter singular nominative/accusative form.
It is a loanword—a word borrowed from another language. Τατουάζ comes from the international word tattoo.
In Modern Greek, it is treated as a neuter noun, which is why it takes το and matches with μικρό in the neuter form.
A useful thing to notice is that some borrowed words in Greek do not change much in form across cases, especially in everyday speech.