write vs write in

write and write in both are verbs.

Word	Noun	Adjective	Verb	Adverb
write	No	No	Yes	No
write in	No	No	Yes	No

As verbs, write in is a hyponym of write; that is, write in is a word with a more specific, narrower meaning than write:

write (verb)	write in (verb)
communicate or express by writing	write to an organization
record data on a computer	cast a vote by inserting a name that does not appear on the ballot
contact in writing
produce a literary work
mark or trace words or symbols on a surface
write or name the letters that comprise the conventionally accepted form of (a word or part of a word)
write music
create code, write a computer program