The Pre-Socratic period of the Ancient era of philosophy refers to Greek philosophers active before Socrates, or contemporaries of Socrates who expounded on earlier knowledge.
The Socratic or Classical period of the Ancient era of philosophy denotes the Greek contemporaries and near contemporaries of the influential philosopher Socrates.
The Hellenistic or Post-Aristotelian period of the Ancient era of philosophy comprises many different schools of thought developed in the Hellenistic world (which is usually used to mean the spread of Greek culture to non-Greek lands conquered by Alexander the Great in the 4th Century B.C.).
The Roman period of the Ancient era of philosophy generally continues the classical Greek tradition and is usually considered to end with the Fall of Rome in the 5th Century.
The Medieval period of philosophy represents a renewed flowering of Western philosophical thought after the intellectual drought of the Dark Ages.
The Renaissance period of the Medieval era of philosophy covers, very roughly, the 15th and 16th Centuries. It can be seen as a bridge between Medieval philosophy and the start of Modern philosophy during the Age of Reason.
The Age of Reason period of the Modern era of philosophy is generally regarded as the start of modern philosophy, and roughly equates to the 17th Century.
The Age of Enlightenment period of the Modern era of philosophy corresponds roughly to the 18th Century.
The Modern period of philosophy generally corresponds to the 19th and 20th Century. More recent developments in the late 20th Century are sometimes referred to as the Contemporary period.