A regular office need, the scanner is a quick way to copy a document in a digital format. It is similar to taking a picture but with better results as it is designed for this purpose specifically. With a camera, there is some distortion at the edges due to the lens curvature.
An office need and its variations
A regular office need, the scanner we have come to know today is far from the first ones that were developed the mid-1800s. The more complete name being Image Scanner, although modern ones can also scan 3D objects. The office scanner is most commonly a 'flatbed scanner', but if one is to achieve the highest possible resolution in a scan then a drum scanner is used. Even though drum scanners are older technology they are more about quality, the newer ones being faster for tasks that do not require extremely high resolution.
Digital cameras can also be used for speed and to not damage the spine of a book, but the downside is possible blur from a shake, a degree of distortion due to the curvature of the lens and shadows. In the scanner, as the light is uniform over the flat surface it is more a true image of the page. There is also a range for scanners designed specifically to scan a bundle of documents as they have a paper feeder akin to a printer that lets a wad of documents go through a page at a time. These help when dealing with a large volume at the office, changing each page would consume a lot more time if one had boxes full of files to convert to a digital format. Some scanners also combine the ability to capture 3D objects well, as they have sensors to capture the multiple layers of information in 3D objects.
Resolution, file formats and dynamic range
The optical resolution claimed by the brands is usually not accurate, the effective resolution is mostly somewhere a good 30 or 40 per cent less. After the scanner is done you have the option of saving files in different formats depending on your requirements relating to file size and resolution. JPEG images and PDF files are smaller and naturally lesser in resolution.
A common high-resolution image format is TIFF, these files are also a lot larger in size so not always convenient. The scanners ability to differentiate between the shadows and highlights is important as well; this dynamic range defines how well the complete image shall look in comparison to the actual document or object. If one is going to use a scanner to scan developed film then a higher dynamic range will capture the shade and colour variations in the image a lot better.
Considerations and general
Connecting to a computer by USB or Firewire is common helping the overall across board connectivity. In current times, as with most things, there are also portable scanners that one has to swipe over the page as it captures information. Various brands also develop scanners that come combined with a printer giving them the ability to work as photocopiers as well, scanning and printing in one go. Fujitsu, Canon, Brother, Epson, Kodak and CZUR are some of the brands on the frontline of scanner production.
The prices vary a lot based on the specific features and brand of the scanner. One can choose based on their needs and the budget they have in mind.