In a computer, images are divided into two types, raster and vector. A raster image that is a grid (mosaic) of pixels—colored dots (usually rectangular) on a monitor, paper, or other display devices. Vector graphics is a way of representing objects and images (description format) in computer graphics, based on a mathematical description of elementary geometric objects, usually called  primitives , such as points, lines, splines, Bezier curves, circles and circles, polygons.

Ratsrovye

• BMP or Windows Bitmap - usually used without compression, although the RLE algorithm can be used.
• GIF (Graphics Interchange Format) is a legacy format that supports a maximum of 256 colors at a time. Still popular for its support for animation, which pure PNG lacks, although software is starting to support APNG.
• PCX is an obsolete format.
• PNG (Portable Network Graphics) is a raster format based on the Deflate compression algorithm.
• JPEG-LS in lossless compression mode - the algorithm uses adaptive prediction of the value of the current pixel based on the environment, which includes already encoded pixels.
• Lossless JPEG is a fast but ineffective compression algorithm that uses (when traversing the image pixel-by-pixel from left to right, top to bottom) a simple non-adaptive prediction of the value of the current pixel based on the values ​​of the top, left and top left pixels

• TIFF supports a wide range of color depths, different color spaces, different compression settings (both lossy and lossless), etc.
• Raw stores information directly obtained from the sensor of a digital camera or similar device without applying any transformations to it, and also stores camera settings. Allows you to avoid loss of information when applying various transformations to an image (loss of information occurs as a result of rounding and pixel color going beyond the permissible values). Used when shooting in difficult conditions (low lighting, inability to set white balance, etc.) for subsequent processing on a computer (usually in manual mode). Almost all semi-professional and professional digital cameras allow you to save RAW images. The file format depends on the camera model; there is no single standard.

Vector

• SVG is the recommended format for use on Wikipedia.
• EMF
• CDR.
• CGM.
• DXF.
• OpenVG.
• GXL is a rarely used format.
• WMF.
• EPS.
• PDF.
• AI.
• SWF - (Small Web Format; previously stood for Shockwave Flash, which caused confusion with ShockWave) a standard extension for compiled Flash files (animation, games and interactive applications). SWF files can be viewed using the free players Gnash or swfdec. To create and work with SWF files, you can use the free command line software package SWFTools.
• DXE.
• F.L.A.

Pre-press layouts must be agreed upon with the company executing the order. Modern equipment works without problems with the PDF format. TIFF is also often used, especially for large format printing. Sometimes they ask for a PSD raster image and a vector AI or CDR image so that they can adjust it to the required size themselves.

Let's start with what kind of image, for example, converting a photo into a vector makes sense only in rare cases. More often this is needed for logos and the like; an image is taken and traced in specialized software.

Yes, now there are a lot of services that do this online. You simply drag and drop the photo and then download the compressed image back. Good service  tinypng

Resolution is a value that  determines the number of pixels of raster image elements per unit area (or unit length). The term is usually applied to images in digital form. For example, a photo on a computer measuring 800x600 pixels. 

To do this you can use a similar service

Now it is fashionable to talk about image banks, as an example of the popular  Flaticon .

If you have an image only in paper form, you need to scan it, then try to enlarge it or convert it to vector format; if it is a photo, then to TIFF format. It all depends on the quality of the original!

Yes, of course, such software exists ,  for raster graphics  Gimp , and for vector  graphics Inkscape , the Russian language is present everywhere.