Ecological succession is the gradual process by which communities of organisms change and develop over time in a given area, from pioneer species to the final stable community.

The entire sequence of communities that follow one another during succession in a given area is collectively called a Sere (or seral sequence). Each transitional community in the sequence is called a seral stage or seral community.

A Climax is the final, stable community that succession arrives at — it is just one community (the last), not the entire sequence.

Ecesis refers to the process of establishment and growth of organisms in a new area — it is a step within succession, not the whole sequence.

Invasion refers to the arrival of organisms into a new habitat — again a single process, not the full sequence of communities.

Hence, the entire sequence of communities successively changing in a given area during ecological succession is called a Sere.