Usability testing is a technique used to evaluate a product by testing it with representative users. In the test, these users will try to complete typical tasks while observers watch, listen and takes notes.
Your goal is to identify any usability problems, collect quantitative data on participants’ performance (e.g., time on task, error rates), and determine participant’s satisfaction with the product.
via Usability Testing | Usability.gov.
This website page illustrates why even a very small amount of website testing is far superior to no website testing at all. You are all at the stage in your website developments where you can email friends and relatives a hyperlink to your website and ask for feedback. Think of what will be easiest for your testers. Perhaps a simple phone call while they are looking at the website will flag up some issues which you had not considered.
Website testing is a developmental tool, not just a tool to be used at the end of the process to justify your design decisions.
Usability Testing with 5 Users (Jakob Nielsen’s Alertbox).