diff --git a/README.md b/README.md
index 1e7976a..f51c005 100644
--- a/README.md
+++ b/README.md
@@ -14,10 +14,36 @@ Maybe having a file per table instead of per database is easier to set up, but i
 
 ### Format
 
-| Offset  | Description |
-|---------|-------------|
-| 0       | Something   |
-| todo!() | todo!()     |
+#### Header
+
+| Offset  | Length  | Description                       | Example                                            |
+|---------|---------|-----------------------------------|----------------------------------------------------|
+| 0       | 16      | Engine Version                    | MyDB-0.0.1                                         |
+| 16      | 14      | Db Version                        | YYYYMMDDhhmmss                                     |
+| 30      | 64      | Table of Tables offset            | Default: 512                                       |
+| 94      | 64      | Table of Users offset             |                                                    |
+| 158     | 64      | Table of user to table            |                                                    |
+| 222     | 1       | Page Size as power of 2           | Default: 14 == 16,384 bytes<br>max 2<sup>255</sup> |
+| 223     | 289     | Nothing                           |                                                    |
+| 512     | 16284   | Default offset of table of tables |                                                    |
+
+The table of tables contains the names and offsets in the file of all tables, or rather the first page of all tables.
+Each table name can have a length of 32 bytes, the offset is a 64 byte integer and there is a 32 byte id so each row in this table is 128 bytes long.
+
+The table of users contain the username and encrypted password of a user. Each username and password can have a max length of 32 and 60 bytes and there is a 32 byte id so 124 bytes per row.
+
+The user to table table contains the read and write access of each user for each table. It uses the table of tables id, the table of users id and a byte for read access and a byte for write access. So 66 bytes per row.
+
+Each table takes up at least one default page worth of space. Default page means that page sizes can vary depending on the table. A table with columns using up a ton of space might need more space per row than the default page size, there it wouldn't make much sense (I think) to have a static page size
+
+#### Page
+
+| Offset             | Length | Description                           | Example                                            |
+| (from page offset) |        |                                       |                                                    |
+|--------------------|--------|---------------------------------------|----------------------------------------------------|
+| 0                  | 64     | Number of pages                       | Default: 1                                         |
+| 64                 | 1024   | max 32 columns * 32 bytes per name    |                                                    |
+| 1088               | 64     | 1 byte per column to set as indexed   |                                                    |
 
 ## SQL Interpreter