aria2 is a multi-protocol & multi-source, cross platform download utility. The supported protocols are HTTP(S), FTP, BitTorrent (DHT, PEX, MSE/PE), and Metalink.
aria2 can download a file from multiple sources/protocols and tries to utilize your maximum download bandwidth. It supports downloading a file from HTTP(S)/FTP and BitTorrent at the same time, while the data downloaded from HTTP(S)/FTP is uploaded to the BitTorrent swarm. Using Metalinks chunk checksums, aria2 automatically validates chunks of data while downloading a file like BitTorrent. More Info »
There are other alternative applications. But aria2 has 2 distinctive features: (1) aria2 can download a file from several URIs(HTTP(S)/FTP/BitTorrent) and (2) If you give aria2 a list of URIs, aria2 downloads them concurrently. You dont have to wait for the current download queue to finish one file at a time anymore. aria2 tries to utilize your maximum download bandwidth and downloads files quickly.