Esri GRID

Grid files that are directly linked to commercial packages will enjoy a low degree of openness, interoperability and robustness.
An Esri ArcInfo Grid (also known as ArcGrid) can use various subdirectories with largely binary files: .adf, .nit, .dir, log, …

It is recommended to convert Grid files to ASCII text. The ArcCatalog from Esri ArcGIS offers “convert GRID to ASCII” options; Surfer has a Grid => Convert => save to GS ASCII option.
Please note: the conversion options are not unlimited nor hassle-free.

Esri GRID is a non-preferred format for file type raster grid.