Use the simple present tense to express facts, states of being, or actions that are occurring now or that occur regularly.
Some common adverbs that typically appear with the simple present are always, frequently, often, sometimes, and usually.
When icebergs calve off heavy glaciers, the broken faces
are always blue.
--"Take It or Leave It," Valley Comic News
As rain-swollen streams flow into a lake behind a dam, there
is a buildup of potential energy, which can be transformed
into kinetic energy as water is harnessed to flow down a
chute.
--C. Donald Ahrens, Meteorology Today
When you use the simple present tense, be careful to use the correct verb form so that you do not produce a subject-verb agreement error.
Use the simple present tense when reporting or summarizing another author's words.
In his book The Universe, Isaac Asimov seeks
to trace the steps by which mankind's grasp of the universe widened and
deepened.You can also use the simple present tense to express future actions that are scheduled to occur. Some verbs that are commonly used in the simple present to express the future are arrive, begin, close, come, end, finish, leave, open, return, and start.
The spring term begins in January next year.
