The present continuous tense, also called the present progressive tense, is used to describe actions that are happening now or ongoing actions. It is formed by using the present tense of the verb "to be" along with the present participle of the main verb. Some examples of the present continuous tense include "I am writing", "she is drinking", and "we are watching". The tense can also refer to actions that will happen in the near future, like "he is going to the library".