Here are 2 complete sentences:
sn hv sp v
Mark was scared. He wanted his mom to come home.
Both are complete sentences because each has a subject, a verb, and is a complete thought.
There are several ways we can combine these 2 sentences.
Coordinating Conjunctions
Mark was scared, so
he wanted his mom to
come home.
A comma isn't enough glue to hold
2 sentences together, so it needs more glue (a fanboy).
Subordinate Conjunction
-at the beginning
Because Mark was scared,
he wanted his mom
to come home.
Subordinate conjunctions
are a lot of glue,
but you can't have
2 sentences rubbing
against each other.
They need the comma
there so they don't touch.
Subordinate Conjunction
-in the middle
Mark wanted his mom
to come home because
he was scared.
The big fat conjunction is between the 2 sentences, so no comma is needed.
Semicolon
Mark was scared; he
wanted his mom to
come home.
A comma isn't enough
glue to hold 2 sentences
together, so we added
another dot of glue.
This makes the comma
into a semicolon.