| Extension | PSD |
| Full Name | Adobe Photoshop |
| Type | Image |
| Mime Type | image/vnd.adobe.photoshop |
| Format | Binary |
| Opens With | Photoshop |
PSD files are the native format used by Adobe Photoshop, one of the most popular image editing applications available. As Photoshop is still under active development, the PSD format is also being enhanced with each new release.
Within a PSD file are the various elements that make up a Photoshop document, from images and text to document metadata; these are all stored in the proprietary PSD format. PSD files also support layers, allowing elements to be edited individually without affecting elements on other layers.
As PSD files are primarily designed for use with Photoshop, for maximum compatibility, Photoshop is best placed to edit them. Other image editing applications can open PSD files, though not all features may be supported.
The STL, or Standard Triangle Language, file format has been around since the '80s and is supported by most modern 3D modelling applications. In particular, the STL format has become something of a standard format within the area of 3D printing, despite the rise of more modern formats such as 3MF.
STL files come in two flavours: binary or text format. The text format is human-readable, making it easy to perform manual edits, but can lead to very large file sizes. As you can imagine, the binary format is much more compact and represents the majority of the STL files you are likely to encounter.
The format itself is very simple; the 3D model is represented by a sequential list of triangles, with each triangle defined with 3 points consisting of their X, Y, and Z positions, along with an additional vector that contains the face normal (the direction the face is pointing). There is an additional attribute block for each triangle; however, this is largely unused and thus unsupported.
