When u do single-file encryption or other things like that.. as in WinZip/WinRar.. what happens is everytime u give a password... the sw works on it to encrypt & decrypt(takes a lotta time to do so & that too for each file).
But TrueCrypt (& Bestcrypt) makes containers (call them drives) within which u can put data to b safeguarded like u copy/paste to a regular drive. U only need to open the container when u want it (which happens in a jiffy). Cut/copy/paste/view whatever u want... & then dismount the drive.
TrueCrypt-encrypted volumes are like normal disks. You provide the correct password (and/or keyfile) and mount (open) the TrueCrypt volume. When u work on a file in the container, TrueCrypt is actually decrypting the file spontaneously in ur RAM, called on-the-fly encryption/decryption.
It's like attaching a password protected USB drive (of whatever size v specify) to the system. Only thing.. the USB drive is actually a container-sorta file made by the specified software. Totally transparent ot any other software, meanin... u just need to mount the container with the correct password & a drive is opened which has the contents of ur container. U can directly run the concerned application u want for that given file... like media files with the media player, word files with MS Word or whatever... as u use a regular usb drive.
