Two roads diverged in a yellow wood
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could

 As the speaker is walking through a wood full of yellow fall trees, the road divides. Which path should he take and where will it take him? What if he chooses wrong?  Existential  dread — that is the initial confusion in the face of an apparently meaningless or absurd world! 
 
 This famous opening line contains possible echoes of other classic poetry. Frost may be thinking of Shakespeare’s  Macbeth  (Act 5, Scene 3) , in which the title character complains: “My way of life / Is fall’n into the sere, the yellow leaf.” If so, that would suggest that this is a midlife poem, whose speaker is past the age (the spring/summer of youth) at which he can casually “start over” on new paths. Frost may also have in mind the opening of Dante’s  Inferno , which describes the original midlife crisis: 
 Midway upon the journey of our life I found myself within a forest dark, For the straightforward pathway had been lost. (Henry Longfellow trans.) 
 (For a similar allusion, see Frost’s  “Birches.” ) 
 Alternatively, early spring buds are usually yellow-green, a sign that this is a poem about spring and starting out on life’s journey, rather than middle age. It is open to interpretation. 
 This opening line alludes to the many metaphorical “roads” a person takes in life, with roads symbolizing the various choices a person faces and makes. At the time of making a choice, one may not know what the long-term implications may be, but philosophically, every decision on which “road” someone decides to take could inevitably play a role in the overall direction of ones' life.
The Road Not Taken