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A '''compiler''' is a [[computer program]] which translates [[source code]] written in a high-level [[programming language]] into executable [[machine code]].  The act of doing this is called [[compilation]].

A '''compiler''' is a [[computer program]] which translates [[source code]] written in a high-level [[programming language]] into executable [[machine code]].  The act of doing this is called [[compilation]].

There are compilers for the more common programming languages available on a wide variety of different computer architectures.  This means that a program written in one of these languages is ''portable'' and can generally be used on any of the different machines just by using the appropriate compiler; note that there may be occasional problems with machine-dependencies, especially if there are substantial differences in the accuracy and size of numbers on the different machines.

There are compilers for the more common programming languages available on a wide variety of different computer architectures.  This means that a program written in one of these languages may be ''portable'' and can often be used on any of the different machines just by using the appropriate compiler; note that there may be occasional problems with machine-dependencies, especially if there are substantial differences in the accuracy and size of numbers on the different machines.

Some compilers just perform a fast simple-minded translation from high-level source code to low-level machine language, while other compilers may optionally take (much) longer to perform the compilation by trying to improve or optimise the resulting machine code.   

Some compilers just perform a fast simple-minded translation from high-level source code to low-level machine language, while other compilers may optionally take (much) longer to perform the compilation by trying to improve or optimise the resulting machine code.