Spring is the transition time between winer and summer. Spring and "springtime" refer to the season, and also to ideas of rebirth, renewal and regrowth. The specific definition of the exact timing of "spring" varies according to local climate, cultures and customs.
In spring, the axis of the Earth is increasing its tilt toward the Sun and the length of daylight rapidly increases for the relevant hemisphere. The hemisphere begins to warm significantly causing new plant growth to "spring forth," giving the season its name.
In recent decades season creep has been observed, which means that many phenological signs of spring are occurring earlier in many regions by a couple of days per decade.
Spring as seen as a time of growth, renewal, of new life (both plant and animal) being born is a term also used more generally as a metaphor for the start of better times.
September 1 is Spring Day here in Southern Africa. In August and September, nature puts on a brilliant display of wildflowers along the West Coast of South Africa. You literally see carpets of flowers of many hues, stretching to the horizon. South Africans and tourists alike make the pilgrimage to see this wonderful display.