I'm writing to complain about the letter you wrote asking for information that I've already written to you about.

I've written lots of books and now I'm writing another one but I need lots of time to write it.

People seem to have lots of problems with spelling the word 'writing.'
So we're going to look at the spelling rules around this word and write, written and wrote.

write is a verb: to write, I write, he writes, she writes, they write...
Notice the "i" is a long sound and says its alphabet name "eye". This is because of the silent 'e' at the end of the word which makes the vowel sound long and say it's alphabet name.

We have the short vowel sound in writ and when we add the silent "e" it makes it a long vowel sound write

When we add -ing to write we drop the 'e' (remember drop the 'e' with -ing rule. Have you seen the video?)

write + ing so drop the 'e' = writing

Writing still keeps its long vowel sound.

We also drop the 'e' in writable, a rewritable DVD

The past tense of write is wrote: I wrote, you wrote, she wrote, he wrote...

Notice again the silent 'e' magic 'e' makes the vowel long and say its name "oh"

Let's look at written

Written is a past particle - I've written to the bank, she's written, they've written to me.

It's also an adjective - the written word, written records

Written has a short vowel sound - the "i" is short that's why we have a double "t" to indicate this short sound.

Double letters after a vowel usually indicate a short vowel sound which helps with reading, spelling, speaking. It was introduced centuries ago.

Double letters dropped out of fashion at the end of most words but when we add a vowel suffix ending we double up the end consonant to keep, or make a short vowel sound:
put - putting
sit - sitter
jog - jogging
quiz - quizzical
writ - written

So we have a long vowel sound for write
and when we add -ing we drop the 'e' to make writing

We have a short vowel sound in writ and double up the "t"
to make written