Modern is a term to describe something of the present, but modernity is a lot messier.
The word “modern” was first used to describe a time period by a Roman statesman and historian of the 6th century CE named Cassiodorus. Like his father, he was an advisor to the Ostrogoth Kings who had taken over southern Italy as the Western Roman empire slowly fell apart. At the end of his career, Cassiodorus retired to his estate and founded a monastery called the Vivarium in order to preserve Roman culture and texts from ancient scholars. He is cited as the first writer to use the word “modernus” (Latin) to regularly describe his own time.
The term was used on and off by different European writers to describe their times throughout subsequent centuries. The Italian Renaissance was a movement in which Europeans began to distinguish their cultures from the standards and structures of the Middle Ages, which were defined by feudalism and religious domination of education and politics. Renaissance scholars translated and circulated texts about ethics and arts from ancient Romans, Greeks, and others, that did not rely on Christian works.
This dynamic played out around Europe in various locales over the following centuries and it largely defined the Enlightenment. Between roughly 1700-1800 this movement fueled secularism, nationalism, and capitalism.
In history the Early Modern era is roughly 1490-1780, and the Modern Era is roughly 1780-1960. But this is not the same as Modernism, a literary and artistic movement of the 1900s wherein writers and artists, again largely in Europe and nations founded through European colonialism, broke with cultural traditions as their societies industrialized and urbanized. The term “modernity” is used in all these contexts, sometimes to mean very specific things, or just as often, wildly vague phenomena.
Modern
Modernity
Modernism
Clear as mud, right?
Just wait for Postmodernism.
Sources:
Modernity- Wikipedia
Introduction to the Renaissance- M.A.R. Habib, Rutgers University