BL (or similar) may refer to:
A blog (a truncation of the expression weblog) is a discussion or informational website published on the World Wide Web consisting of discrete, often informal diary-style text entries ("posts").
Blu-ray or Blu-ray Disc (BD) is a digital optical disc data storage format. It was designed to supersede the DVD format, in that it is capable of storing high-definition (720p and 1080p) and ultra high-definition video resolution (2160p).
Bluetooth is a wireless technology standard for exchanging data over short distances (using short-wavelength UHF radio waves in the ISM band from 2.4 to 2.485 GHz) from fixed and mobile devices, and building personal area networks (PANs).
Blade Runner is a 1982 American neo-noir science fiction film directed by Ridley Scott, and starring Harrison Ford, Rutger Hauer, Sean Young, and Edward James Olmos.
A black hole is a region of spacetime exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it.
The blue whale (Balaenoptera musculus) is a marine mammal belonging to the baleen whales (Mysticeti). At up to 29.9 metres (98 ft) in length and with a maximum recorded weight of 173 tonnes (191 short tons) and probably reaching over 181 tonnes (200 short tons), it is the largest animal known to have ever existed.
Blue is the colour between violet and green on the optical spectrum of visible light. Human eyes perceive blue when observing light with a wavelength between 450 and 495 nanometres, which is between 4500 and 4950 ångströms.