What’s the meaning of "milestone"?

Native speaker’s answer
Rebecca
A "milestone" is a celebration-worthy event or action that marks a significant achievement, success, or development. For example, we might consider some basic, common milestones for people to include graduation, marriage, and retirement. James Corden has used "milestone" to describe Ariana Grande's achievements in music, as the time she occupied numerous number one spots on the Billboard Charts. Ex: Thank you all for attending our wedding. We are delighted to have you here to celebrate this milestone. Ex: The Paris Agreement is considered to be a milestone for climate action cooperation.