You must have read or heard about wget command line download utility. It provides  immense capabilities, but when it comes to accelerating the download speed, wget doesn't provide any option. But Axel is one such tool which do the job of a download accelerator very well.
Axel does the same thing any other accelerator does: it opens more than one HTTP/FTP connection per download and each connection transfers its own, separate, part of the file.

Downloading Axel

For Ubuntu Axel is available in the default apt repositories, open the terminal and issue the following command.
  • $ sudo apt-get install axel

Using Axel

Download from multiple locations
  • $ axel <url1> <url2> <url3>
This will use all these mirrors to download the file.

Limit the download speed
  • $ axel -s 3000000 <url>
Mention the speed in bytes per second.

Limit the number of concurrent connections or threads
  • $ axel -n 3 <url>
Change the name of the output file
  • $ axel -o output_file.ext <url>
Mentioning a directory will save the file in that directory.

View the download information of each connection or thread
  • $ axel -a n 3 <url>

Thanks for reading :-)