STP (Simple Theorem Prover) is a constraint solver (also referred to as a decision procedure or automated prover) aimed at solving constraints generated by program analysis tools, theorem provers, automated bug finders, intelligent fuzzers and model checkers. STP has been used in many research projects at Stanford, Berkeley, MIT, CMU and other universities, as well as companies and government agencies.

The input to STP are formulas over the theory of bit-vectors and arrays (this theory captures most expressions from languages like C/C++/Java and Verilog), and the output of STP is a single bit of information that indicates whether the formula is satisfiable or not. If the input is satisfiable, then it also generates a variable assignment to satisfy the input formula.

Additional information can be found here.