Why does language change? Give minimum five reasons.

Language changes because of people's exposure to other
languages. English, for example, has added words from all over the world.  This goes
back to the various conquering of the British Isles, by the Scandinavians, by the
Romans, and by the Normans.  And we have been adding words from other languages ever
since.

Languages change because people move. When they do
so, they experience new experiences, see new flora and fauna, and the longer they are
away from their original people, the more the language tends to
change.

Language changes because of science and technology.
We need new words to describe the things we discover and invent.  Hebrew is a good
example, an ancient language used only for religious ritual until the founding of the
state of Israel.  There were no coffeemakers or computers in the
Bible.

Language changes because of youth.  Young people
want to express themselves in their own "language," a way of being separate from the
older generation, which is what much slang is for.  Eventually, some of this slang
enters the mainstream language, at which point our youth have to invent new
slang.

Language changes because of politics.  The terms
used in the political arena frame issues in ways that are meant to poison the well.  New
terms and expressions arise, some quite interesting, some quite distasteful, but we have
gone from "atom bombs" to weapons of mass destruction.  Orwell commented on this in a
rather famous essay in 1946.  I have included a link to the essay
below.

There are other reasons, some having to do with
"drift" in consonants and our general tendency to laziness, always looking for an easier
and faster way to say something.  Sometimes new words are simply erroneously heard, for
example the word "nickname," which experts have theorized comes from the term "an eke
name," a combination of words which kind of slid together over time.  Sometimes words
change completely in meaning, such as the word "awful," which used to mean "full of
awe."  This is likely to have happened because something terrible can fill one with
awe.  There are other reasons, which have filled books, but I hope this is a good
start.