The hashing algorithm BCrypt is a hashing function that was created from Blowfish algorithm by two people, Niels Provos et David Mazières. This hashing function has several advantages, first of all it uses natively a random salt (a salt is a sequence that you add to a password to make it more difficult to bruteforce). This random salt prevents the creation of lookup tables, like the one we're using on this website for less secure hashing functions such as md5, sha1, etc. Actually, a lookup table could be created, but it would demand a tremendous amount of hardware power, as a huge disk space, because you'd have to store each different salt for each word you want to encrypt. The lookup itself would demand a lot of ressources.
The other advantage of BCrypt is that you can choose the amount of iterations to make it slower on purpose, and so harder to bruteforce. With the hardware going, one could imagine that one day BCrypt won't be secure anymore, as of now it remains one of the most secure hashing algorithm. One day perhaps we could see fast and reliable Bcrypt decrypt online, but as of now, decrypting Bcrypt is way too hard using traditionnal online tools such as Rainbow tables.