Let’s try to explain in the simplest way possible what a Zip file is.
A Zip file is a type of file that can contain and compress other files and folders. It can be used to create a data store by reducing the original storage space of the contained items in order to reduce transfer times over the network or between different computers.
In practice, it is a file capable of storing other data by compressing the total size of the elements present inside it without losing any type of information.
To better understand what a Zip file is, in the first part of the guide we will explain what an archive file is and what lossless data compression is, while in the second part we will see what the characteristics of the Zip format are.
- Archive file and data compression
- Features of Zip files
- How to create a Zip file
- How to open a Zip file
Archive file and data compression
An archive file (archive file in English) is a special type of file that consists of one or more files and metadata. Metadata is information that describes and provides information about other data.
Thanks to the ability to store directory structures, archive files allow you to collect and compress multiple data files into a single item at the same time. This allows for easier portability and archiving as compressed files use less storage space.
The data lossless compression (in English lossless compression) is a data compression type. Its characteristic is that it does not lose any type of information during the compression or decompression of the data. It is mainly used to compress text documents, executable programs and in all those situations where it is of fundamental importance that the original data and the decompressed data are identical.
An example of lossless compression is the Zip format.
Features of Zip files
A Zip file is an archive file type that supports lossless data compression. It allows the use of different compression algorithms that allow to reduce the amount of bits used by the original digital information. Thanks to its performance and the absence of patents, the most widely used algorithm is the Deflate.
A Zip file can take up less storage space than an uncompressed file, resulting in faster transfers across networks and between different computers.
The “zipped” files can be used in the exact same way as the non “zipped” files but with the possibility of combining multiple items in a single compressed folder and are mainly used to compress and send files that could be altered during the compression process.
The reduction in storage space made by compression is not the same for all data but depends on the type of file. For example, for the characteristics that distinguish them, text files are suitable for compression while image files are not at all.
The Zip format, developed by the US computer scientist Phil Walter Katz in the late 1980s when the storage capacity of hard drives was far less than today’s, has been implemented by many software since its origins.
Microsoft has included support for the Zip already in early versions of Windows under the name of compressed folders while the operating systems Mac have included it in 2003 with the Mac OS version 10.3.
Windows “zipped” files are recognizable by an icon characterized by the presence of a “zip” hinge and the extension is normally used. zip zip
In the .zip format, each file is compressed separately allowing you to use different compression methods for the same file archive. Thanks to this feature it is possible to extract or add new files without compressing or decompressing the entire archive.
The .zip format uses the 32-bit CRT algorithm and includes two copies of the directory structure to decrease the possibility of data loss.
How to create a Zip file
To create a “zipped” file we need to compress files and/or folders within a .zip archive.
To do this we need software capable of creating an archive file using data compression. The programs capable of creating a Zip file are many, free or paid. Among the free ones, the most used is 7-Zip while the most popular paid are WinZip and WinRAR .
How to open a Zip file
The “zipped” files cannot be opened or executed directly but must first be unzipped. The Zip file is only a container. Before being able to use the files or folders contained within it, we must extract them that is to restore them to their original state.
Any software capable of creating a Zip file can also be used to extract items from the archive.