As download or download is known in the electronic data processing (EDP) receiving data on your own computer , the client , via a network , usually the Internet , from a server come. The data transmitted or made available for transmission are also referred to as downloads. In contrast to calling up a website or streaming a video , the aim and result of a download is the permanent storage of the data downloaded, usually a single file , on the user's device. The download or the download is the counterpart to the upload or the upload .
Since the widespread use of fast Internet connections , downloads have played an increasingly important role in the commercial distribution and private exchange of digital goods such as software , music , films and e-books . In addition, downloads have largely replaced the previously common distribution in paper form for many types of documents, for example technical documentation , industry standards and norms , product catalogs , scientific studies and more extensive operating instructions .
The basic principle of the download is to actively request one or more files that are offered or made available for download by a provider and then to receive and save them on your own device. The own device that receives the data is often a personal computer , smartphone or tablet computer .
On the other hand, the basic principle of uploads is that the provider actively sends (“uploads”) one or more files from their own device to a remote station that receives the files. Often the receiving partner is a server or host .
The file transfer protocol FTP , established in 1985, serves as the Internet Protocol (IP) for downloading and uploading files, as well as a number of special applications. However, when data is downloaded from a website on the World Wide Web , the FTP is interrupted to ask the user for the desired storage location. After confirming the storage location, the transfer will continue.
The communication protocol HTTPS is a secure hypertext transmission protocol and is used for the encryption and authentication of the downloaded or uploaded data between the server and the client. The authentication is used to ensure that each side can verify the identity of the connection partner and secure data transmission takes place.
The integrity of the downloaded file can be checked using hash values (scatter value function values). The provider of a download creates checksums according to the Message-Digest Algorithm 5 (MD5) developed in 1991 , which are provided as separate files, for example. After the transfer has been carried out, the error-free transfer is verified by the recipient using a special program to create the MD5 checksum from the transferred file and comparing it with that of the provider. If both sums match, there is an extremely high probability that the data transfer has been completed. However, the downloaded file can still be faulty or infected with malware (malicious program) and computer viruses , as the MD5 function is no longer considered secure, as it is possible to generate different messages with the same MD5 hash value with a manageable amount of effort .
The term download is often interpreted generally to mean that received data is stored permanently or at least should only be stored temporarily.
In contrast, the term download is taken from the related data transmission method of streaming , which means that received data can be used immediately while the transmission is not yet complete. If the general definition of the term download were to apply, it would mean that the data can only be used if they have been received in their entirety.
In this context, download specifically means “receive and save” instead of just “receive”.
Another important criterion for differentiation is the data transmission by email . When sending data by email, this data is only sent as an attachment (attachment). It is not a download in the specific sense.
A download always depends on the available data transfer rate between server and client. On the one hand, this has an absolute limit in the physical limits of the respective transmission channel or in the specifications of the respective devices. On the other hand, when using the Internet, however, it is more relevant that the provider or providers between client and server in most cases deliberately throttle the data transmission rate in order to ensure that customers are treated consistently.