What is an FPGA?

A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by a customer or a designer after manufacturing—hence "field-programmable". The FPGA configuration is generally specified using a hardware description language (HDL), similar to that used for an application-specific integrated circuit (ASIC) (circuit diagrams were previously used to specify the configuration, as they were for ASICs, but this is increasingly rare). Contemporary FPGAs have large resources of logic gates and RAM blocks to implement complex digital computations. (https://en.wikipedia.org/wiki/Field-programmable_gate_array) The following video, recommended by John, KM6QX from EVVBlog is a nice tutorial describing what a FPGA is and how it operates on a technical level (http://www.eevblog.com/2013/07/20/eevblog-496-what-is-an-fpga/)