Alpha Test:  The first test of newly developed hardware or software in a laboratory setting. When the first round of bugs has been fixed, the product goes into beta test with actual users. For custom software, the customer may be invited into the vendor's facilities for an alpha test to ensure the client's vision has been interpreted properly by the developer.

Beta Test: A test of new or revised hardware or software that is performed by users at their facilities under normal operating conditions. Beta testing follows alpha testing. Vendors of packaged software often offer their customers the opportunity of beta testing new releases or versions, and the beta testing of elaborate products such as operating systems can take months

A successful test provides following goals:

1) Detect maximum bugs

2) Deliver the s/w or system meeting all the specified requirements
3) User satisfaction
4) Quality s/w delivery
5) Risk related to software or system are reduced which can lead to system failure and also prevents major loss to organization developing s/w.

How will you test a keyboard?

First of all I will go through all requirements.
After that I will check first positive than negative way.
I will give valid strokes (press all keys) ensuring all keys working correct or not.
I will check combination keys are working correct or not.
I will check invalid strokes ex: pressing key "a" and "c" at a time.
I will check functional keys working.