It is not only a database, although it might need an interface much like one. But it surely does extra issues.
To begin with the chain helps very effectively examine your state of the database with others. A single 32-byte worth “summarizes” your entire state in a cryptographically safe approach, in order that if a number of folks come collectively and examine their hashes with one another, in the event that they match, they know that all of them have precisely the identical view of the database. There are different methods to summarize a database like this, utilizing timber and so on that could be extra environment friendly for databases you wish to learn and write to, however a linear chain is essentially the most environment friendly approach for databases the place you solely wish to write further information to.
A second necessary property of the Bitcoin blockchain particularly is that proof-of-work is added to every block within the chain. Which means within the case the place completely different folks have completely different of those summaries, now we have a really dependable approach to come to settlement on which one among them is the one we wish to take a look at. If within the room a number of summaries are introduced, everybody can simply come settlement on a single one in a approach that can (a) all the time work and (b) may be very laborious to take advantage of by a cheater that wishes to persuade folks to have a look at the incorrect one.
However finally, the query could possibly be “why do we have to maintain all transactions since ever within the first place?”. That is a legit query. In concept, these summaries may simply summarize the present “state” of the database, not all of the historical past. And we’d have the identical system to determine between histories utilizing the proof-of-work. However then we’re trusting the miners that create the proof of labor to make trustworthy summaries. The objective of Bitcoin is to attenuate belief in unknown third events, so all historical past is saved since its inception so that everybody that participates can reconstruct the state of the database by replaying all transactions.
So to conclude, the blockchain is actually the factor that allows Bitcoin to run in an nearly utterly trustless approach, the place all contributors can do all verification on their very own and the proof-of-work is simply wanted to make them determine between two completely different equally-valid states. This fashion now we have a really strong system of forming consensus on who owns which cash and who’s allowed to spend it.