TinyPDF is a PDF document creation tool for Windows. The application does not install a user interface of any kind. It simply installs itself as a printer device on your computer. From there, the application can create PDF documents from any application with printing support.
For example, if you want to create a PDF file off a .DOC file, all you have to do is open that document in Word and print it. You have to use the TinyPDF printer icon as your printer, though. When you do that, TinyPDF will output a PDF file that can be opened with any PDF reader out there. Creating PDF files with TinyPDF does not require Adobe Acrobat or any other application to be installed on your system.
The PDF files that are created with TinyPDF conserve most of the formatting of the original file, when possible. I tested it with a web page and most of the text and images contained therein looked the same in my PDF, but there were some slight changes. If you convert a .DOC file to PDF using this tool, the final PDF will also contain text. I make this remark because some tools simply snap a picture of the text, which results in non-editable or copyable text.
TinyPDF is super easy to use and light, although it doesn't have a user interface and little to no options to play with.