EPS file extension is used by files in encapsulated postscript format. Encapsulated postscript file format was designed to be embedded inside the postscript files. Still it is possible to open EPS file without having it embedded into another document.
To open EPS file and view its contents you can use free Ghostscript software. Ghostscript will execute postscript commands and rasterize contents of EPS file. You can also rasterize EPS file using GIMP, Adobe Reader or Irfan View.
If you don’t want to rasterize EPS file but edit it in vector form, you can use CorelDraw or Adobe Illustrator. Both of these applications will open EPS file in a vector format giving user full flexibility in editing its content and saving it back to EPS or exporting to other supported formats.
Files in EPS format are sent over internet using application/postscript, application/eps, application/x-eps, image/eps, image/x-eps mime types.
EPS file standard requires it to draw its contents within specific boundaries defined in %%BoundingBox line. EPS file without %%BoundingBox command considered invalid. Also, many EPS files will contain a preview picture which will be used by embedding software during image browsing process. EPS files are not supposed to be edited after being embedded. Still they support transformations such as scaling, tilting and rotating the image.
Due to the use of postscript commands EPS file is device independent and can be rendered on any device. But it requires postscript rendering engine to be installed.
EPS file must conform to Document Structuring Conventions (DSC) which is a set of comments allowing to structure postscript documents so they could be manipulated without executing postscript commands.
Technically because EPS file is a fully featured scripting language it can contain malicious code but since rendering of EPS file happens within postscript processing software it limits potential attach exposure. That’s why in general EPS files are considered to be safe for download.