A society is generally considered modern when it is industrialized. Other factors include literacy, being a nation-state and urbanization. Most facets of society have a modern example, such as secularism, for lifestyle.
Modern societies no longer farm or produce products at the subsistence level. Instead, they make products to sell. People typically do not subsist on their own and need to buy items to live. For example, people go to the grocery store instead of owning animals and a garden to provide food. Modern societies show a cultural, liberal growth as well. These societies put an increasing emphasis on equality and education for everyone as seen in the wide-reaching civil rights movements.
Colonization and increasing political elements are also key aspects of modernity. Colonizing areas pulls tribal or traditionalist societies into the modern society standard by starting nations and countries. It also puts an emphasis on politics and distinct economic systems, such as capitalism, that are distinctly different from the traditional barter system.
A move away from spiritualism and traditional religion and toward secularism, atheism and agnosticism are also factors in modernity. This is most notably seen in modern societies that have education as a top priority for citizens. Additionally, modern societies tend to have more superfluous personal possessions.