Diary

Greg Heffley's journal is his biggest job in the Diary of a Wimpy Kid series. Without it, there would be no way to know what happens in his life. So far, there have been seventeen of them. The 1st one is red, 2nd is blue, 3rd is green, 4th is yellow, 5th is purple, 6th is cyan, 7th is brown, 8th is lime-green, 9th is orange, 10th is black, 11th is red-orange, 12th is blue-green, and 13th is violet-cyan, 14th is gray-orange, 15th is blue-dark blue, 16th is gray-yellow-blue, and 17th is black. All of them say DIARY on the cover, Not JOURNAL. Greg explains how he told Susan (his mother) to get one that doesn't say the word diary, but Susan still got one that said diary, probably because it was cheaper or she didn’t hear part of it and thought Greg wanted her to get one that had the word diary on it. All of them have little drawings between the texts based on what Greg's talking about. Each Diary has 217 pages, though some of them also have 17 activity pages, and the activities are extracted from Diary of a Wimpy Kid: Do-It-Yourself Book. In all the descriptions and summaries, it has been labeled as a diary, but it is exactly Greg's journal, and that's how he got mad at his mom for buying that book until Greg saw Rowley's new diary.

All Creditings in The Wimpy Kid Books
In every Wimpy Kid book, Jeff Kinney credits people for ideas that were made into said book, and simply crediting them for other reasons. Here is all the people who were credited for giving ideas or other stuff by Jeff Kinney.

Book 1 - To Mom, Dad, Re, Scott, and Patrick.

Rodrick Rules - To Julie, Will, and Grant

The Last Straw - To Tim

Dog Days - To Jonathan

The Ugly Truth - To Tomas

Cabin Fever - To Tichino

The Third Wheel - To Gram

Hard Luck - To Charlie

The Long Haul - To Pranav

Old School - To Dad

Double Down - To Dorian

The Getaway - To Annie

The Meltdown - To Deb

Wrecking Ball - To Scooter

The Deep End - To Ryan

Big Shot - To Will and Grant

Diper Överlöde - To Scott

Movie Diary (First 3 Movies Edition) - To Zach and Robert

Movie Diary: The Next Chapter - To Jason

Results
Scott, Dad, Will, and Grant have tied at 2 creditings, everyone else has been credited once.

Trivia

 * In Diary of a Wimpy Kid: Rodrick Rules, it was later revealed that Rodrick snatched Greg’s diary and ran, but tripped over a board game. Greg quickly got the diary and went to the Leisure Tower's Women's bathroom without noticing and destroyed the first diary by flushing it in the toilet. Then when the security came and got him out, Rodrick saw the whole thing and blew his secret 4–6 months later, and the story ended up changing to infiltrating the high school cheerleading locker room. As a result, he became very popular.
 * Greg rips out certain pages of his diary, which can be seen in movies and games sometimes. In the first and second Diary of a Wimpy Kid movies, you see pages which were never in the book, meaning Greg probably ripped them out.
 * Considering Greg to be 11 in Diary of a Wimpy Kid (since he was in 6th grade), if the series is not timeless, Greg would be about 13 and almost 14 (by The Long Haul, since it ends in June) but since Jeff Kinney said it's timeless it is very unlikely. If considered 12 then he would be 14 (almost 15).
 * Greg only aged once in Dog Days he is shown celebrating his 13th birthday Greg didn't age or celebrate his birthday on the summers of Rodrick Rules (which we never see it happen)and The Long Haul which would make him 13 and in the 7th Grade.
 * The Long Haul is the first time since Diary of a Wimpy Kid that there are missing months between the current book and previous book, May is missing.
 * Greg considered the diary as a journal.
 * Greg's diary is not mentioned in the books Diary of a Wimpy Kid: Dog Days up to Diary of a Wimpy Kid: The Getaway (except for The Third Wheel and Double Down)
 * Greg’s diary is not mentioned in the Dog Days and The Long Haul films outside of when Greg is narrating it.
 * ​Each diary has its own months. So far in all diaries, there are a total of 53 months, which is the same as 5 years and 3 months.

Chronological order
Diary of a Wimpy Kid: Diper Överlöde (January-April)
 * Year 1
 * Diary of a Wimpy Kid (September–December)
 * Year 2
 * Diary of a Wimpy Kid (January–June)
 * Missing months (July and August)
 * Diary of a Wimpy Kid: Rodrick Rules (September- December)
 * Year 3
 * Diary of a Wimpy Kid: The Last Straw (January–June)
 * Diary of a Wimpy Kid: Dog Days (June–August)
 * Diary of a Wimpy Kid: The Ugly Truth (September–November)
 * Diary of a Wimpy Kid: Cabin Fever (November and December)
 * Year 4
 * Diary of a Wimpy Kid: The Third Wheel (January and February)
 * Diary of a Wimpy Kid: Hard Luck (March and April)
 * Missing month (May)
 * Diary of a Wimpy Kid: The Long Haul (June)
 * Missing months (July and August)
 * Diary of a Wimpy Kid: Old School (September and October)
 * Diary of a Wimpy Kid: Double Down (October and November)
 * Diary of a Wimpy Kid: The Getaway (December)
 * Year 5
 * Diary of a Wimpy Kid: The Meltdown (January and February)
 * Diary of a Wimpy Kid: Wrecking Ball (March-June)
 * Diary of a Wimpy Kid: The Deep End (August)
 * Diary of a Wimpy Kid: Big Shot (September-November)
 * Diary of a Wimpy Kid: Diper Överlöde (December)
 * Year 6