Nicolo Nicoli (1363- 1437) was a famous Italian literati in the Renaissance. Nicli has a private library and likes to collect solitary ancient books. Since there was no photocopier at that time, he saw other people's good books and wanted to borrow them and copy them by hand. A lot of copying improved Nicky's calligraphy level and formed his own unique leaning calligraphy.
After Nicky's death, his fluent calligraphy was adopted by the first printer in Italy and quickly spread to European countries, including Britain, and was called italics.
Not all Italian fonts are inclined, for example, there is a straight Roman style.