RISC-V is an instruction set architecture (ISA) specification. So the standard is really just a definition of some instructions and what they should do. The unique part is the fact it is an open standard and so does not require any licensing or royalties.
This means that anyone can then go away and build their own processor implementation to that standard. Intel could create their own chip for that instruction set and get it running at 4Ghz with your latest fab facility. At the other extreme I could sit at home and use Verilog to create a soft core that is downloaded to an FPGA and be up and running with a much slower implementation). Neither of us has to pay anyone for the right to do so and the code we write should work on both because it adheres to the same standard.
In contrast, if you want to create an ARM or x86 processor then you have to pay a license fee. Even if you implement the entire processor from scratch and use nothing from ARM or Intel except the instruction set specification, you still need to pay and it is not cheap. There are many situations where you want to avoid that cost. A researcher wants to experiment with a new idea, you want an internet of things processor but cannot afford the license cost of an existing processor. Or your Samsung and produce zillions of phones a year and saving that dollar per phone is worth having.
As the RISC-V standard is relatively new it means that the first designs to market are the targets that are easiest to create, so microcontrollers. SiFive are now moving up the scale and are working on a full processor with MMU that could be used to run something like Linux. I would expect to see something like that appear within a year or so.
This means that anyone can then go away and build their own processor implementation to that standard. Intel could create their own chip for that instruction set and get it running at 4Ghz with your latest fab facility. At the other extreme I could sit at home and use Verilog to create a soft core that is downloaded to an FPGA and be up and running with a much slower implementation). Neither of us has to pay anyone for the right to do so and the code we write should work on both because it adheres to the same standard.
In contrast, if you want to create an ARM or x86 processor then you have to pay a license fee. Even if you implement the entire processor from scratch and use nothing from ARM or Intel except the instruction set specification, you still need to pay and it is not cheap. There are many situations where you want to avoid that cost. A researcher wants to experiment with a new idea, you want an internet of things processor but cannot afford the license cost of an existing processor. Or your Samsung and produce zillions of phones a year and saving that dollar per phone is worth having.
As the RISC-V standard is relatively new it means that the first designs to market are the targets that are easiest to create, so microcontrollers. SiFive are now moving up the scale and are working on a full processor with MMU that could be used to run something like Linux. I would expect to see something like that appear within a year or so.