Visible spectrum – is part of electromagnetic spectrum and all light is invisible. We only see the colours of objects the light reflect from.
HSL
HSL is a photographic term used to refer to parts of colour.
Hue – the actual colour like the three primary colours like red or blue:
All colours are made by mixing these three above colours in various combinations to get any colour imaginable.
Saturation – the amount or intensity of colour present
Luminance – refers to the brightness of the colour – when you turn up the brightness control on your phone, you are adjusting the luminance.
Contrast – removes some middle colours and increases the amount of blacks and whites – makes images pop.
Here is a link to Luminar web site where they have a pretty good explanation on contrast. Luminar is an alternative to Photoshop without the monthly fee.
Raw file – an unprocessed image from your computer, usually a large amount of megapixels. The colours tend to be little flat and lack contrast. Raw files need to be edited.
jpeg – often shortened to jpg for stands for Joint Photographic Experts Group. The file is usually about a third the size of a raw file. It is a lossy file meaning that every time you save and share a jpg photo, it is compressed, you loose a little quality.
A jpg file is and edited by the camera in that exposure, brightness and colours are adjusted and enhanced in the camera. That doesn't mean you should let the camera makers and engineers decide how your photos will look. You should always have final say and editing allows you to do that.
JPG 2000 – meant to replace jpg but it never caught on because of copyright and other technical issues.