There were essentially two major phases of Reconstruction. The first is often called Presidential Reconstruction, and lasted until the midterm elections of 1866. The second, which lasted from 1867 to 1877, is known as Congressional, or Radical Reconstruction, though it should be noted that its effects had waned severely by the time Reconstruction was finally brought to an end.
Presidential Reconstruction describes the approach of Andrew Johnson to Reconstruction. Johnson sought to eliminate only the most diehard Confederates from politics, believing that ordinary Southerners (as he himself had been) would control the postwar South. When this turned out not to be the case, and former Confederates were returned to political leadership, he did little about it. He warned against the "Africanization" of the South, opposing political rights for former slaves, and he vetoed legislation that proposed to expand the mandate of the Freedmens Bureau. He also opposed the Civil Rights Act of 1866, and looked the other way as Southern states imposed "black codes," which imposed harsh legal restrictions on African-Americans.
Congressional Reconstruction began when Republicans were swept into Congress in the elections of 1866. Led by a group known as "Radicals," they sought to establish legal, political, and social rights for African-Americans in the South, and to ensure the programs were implemented, they divided the South into military districts, occupied by small contingents of federal soldiers, with the Reconstruction Act of 1867. With federal protection for black voters, many African-Americans were voted into office, especially at the state levels. Despite these advances, no serious proposals were put forth to secure land for freed slaves, who were mostly forced by economic need to accept sharecropper or tenant arrangements on farmlands owned by whites.
Over time, the Radicals lost momentum for reforms, and "redeemer" governments (i.e. white Democrats opposed to Reconstruction) took over state governments, often using violence and intimidation. The final five years of Reconstruction might, in fact, be thought of as a final phase, as whites reestablished white supremacy in almost every southern state. By the time the infamous compromise of 1877 was settled, Reconstruction was in many ways over in the South.