It means Parts Per Million. It is generally used to measure and denote the concentration of chemical in very low quantity. e.g we say the sea water contains 0.5 ppm of pure gold. Or human blood contains 20 ppm of iron oxide. This unit is used when other units like % and fractions are too big to denote the quantity.
ASP.NET Dynamic Data. ASP.NET Dynamic Data is a Ruby on Rails-inspired web application scaffolding framework from Microsoft, shipped as an extension to ASP.NET, that can be used to build data-driven web applications.
Dynamic Language Runtime. The dynamic language runtime (DLR) is a new API in .NET Framework 4. It provides the infrastructure that supports the dynamic type in C#, and also the implementation of dynamic programming languages such as IronPython and IronRuby. For more information about the DLR, see Dynamic Language Runtime Overview.