Which one is the proper alternative ? niche / field / area / domain

I'm developing software that asks user to specify a niche / field / area / domain of the document he is uploading. It can be business proposal, technical documentation, official stuff, correspondence, complain whatever. How do I call this field ? There will be a suggestion form field that will contain the most frequent expressions.

Solution 1:

It could be difficult to pick the perfect label for this field. But based on your description, and as a programmer, I agree with John Satta, Category is probably the safest bet. But some other words which might work:

• Tag
• Description
• Subject
• Topic

Solution 2:

The word most familiar to your users for this function is "category", as in "specify the category for this document". This word, coupled with examples will clearly convey your message.

Another useful word might be "type", but users uploading files might interpret that to mean "which software package created the document" and thus provide answers such as MS Word, Excel, PowerPoint, etc. That is not what you are looking for, as stated in your question.