Bitcoin is the first decentralized currency to appear on the Internet. What it means is that no one really has any control over it. New coins can be issued, but their fate from then on is purely dependant on the people who spend or acquire them. It was also the first cryptocurrency, which then developed in a major trend.
Bitcoin was launched by Satoshi Nakamoto back in 2009 as a project and a statement in favor of currency decentralization (apparently successful). The name is basically derived from the smallest information unit (the bit), reflecting the fact that Bitcoin is simply a digital projection, and not a physical type of money.
The very first Bitcoin logo was an image of a golden coin (a yellowish circle with a prominent rim on the edges) with the letters ‘BC’ in the center written in a paler shade of yellow.
February to November 2010, this was the primary logo used for the currency. The fidelity of the image was increased, and the letters ‘BC’ were replaced by a now-iconic symbol of a letter ‘B’ pierced by to vertical lines – inspired by the symbol of an American dollar ($).
November 2010 saw the logo finalized into the longest-living variant yet. It’s an orange circle with the same Bitcoin symbol painted in white onto its central part. It was also a bit tilted to the right, but that’s about it.
If the project’s name needs to be specified on a logo, they use a writing made in grey. It’s the project’s name (Bitcoin) written completely in lowercase and tilted to the right slightly. It’s also an official image, although it’s used irregularly. Mostly people just utilize the emblem, and that’s it.