Command wget stands for web get. The wget is a free non-interactive file downloader command. Non-interactive means it can work in background when user is not logged in. This allows user to get disconnected with the system while wget finish its work.
It can even download entire website as a local version of remote websites, fully recreating the structure of original website. In short, you can mirror an entire website with wget.
It supports HTTP, HTTPs and FTP protocol. It is a freely available package and licensed under GNU GPL. This command works on all operating systems including MAC Os and Windows.
The main feature of wget is its robustness and recursiveness. Due to its robustness, it work even in slow internet connection. It automatically starts downloading the file from where it was left in case of network failure. Due to its recursiveness, it keeps trying until the file is retrieved completely.
To use wget, you have to give location of the file over HTTP as the wget argument. File will be downloaded in the current directory.
In some systems wget may not be installed. To install wget use the following command,
sudo apt-get install wget