The Agile Manifesto was written by seventeen software development leaders, who gathered together at the Snowbird ski resort in Utah. The group agreed there was an increasing need for an alternative to heavyweight software development processes and, despite having widely varying opinions on the right approach, did find consensus around four core values described below:

“We are uncovering better ways of developing software by doing it and helping others do it. Through this work we have come to value:
1. Individuals and interactions over processes and tools
2. Working software over comprehensive documentation
3. Customer collaboration over contract negotiation
4. Responding to change over following a plan
That is, while there is value in the items on the right, we value the items on the left more.”

They also laid out 12 principles that stand behind these values. Those principles include:
● Satisfying customers through early and continuous delivery of valuable software
● Welcoming changing requirements at any point in the delivery cycle
● Delivering software frequently through shorter development timelines
● Using working software as the primary measure of progress
● Taking regular moments of self-reflection to identify opportunities for improvement

The 4 values and 12 principles continue to guide the Agile approach used by teams today.

Source:
This post was inspired by The History of Agile