Overall .ZIP file format:
[local file header 1]
[file data 1]
[data descriptor 1]
.
.
.
[local file header n]
[file data n]
[data descriptor n]
[archive decryption header]
[archive extra data record]
[central directory]
[zip64 end of central directory record]
[zip64 end of central directory locator]
[end of central directory record]

A. Local file header:

local file header signature 4 bytes (0x04034b50)
version needed to extract 2 bytes
general purpose bit flag 2 bytes
compression method 2 bytes
last mod file time 2 bytes
last mod file date 2 bytes
crc-32 4 bytes
compressed size 4 bytes
uncompressed size 4 bytes
file name length 2 bytes
extra field length 2 bytes

file name (variable size)
extra field (variable size)

B. File data

Immediately following the local header for a file
is the compressed or stored data for the file.
The series of [local file header][file data][data
descriptor] repeats for each file in the .ZIP archive.

C. Data descriptor:

crc-32 4 bytes
compressed size 4 bytes
uncompressed size 4 bytes