A manual traffic exchange is a way of exchanging credits that you earn by surfing and viewing other websites, and then these credits can be used to display your website or business opportunity to others. In addition to earning credits (pageviews) from surfing you can purchase additional credits, or buy a premium membership which will typically add credits to your balance each month. Also with a premium membership you will often get an improved surfing ratio.
Many traffic exchanges also offer the ability to make money when other members upgrade or purchase advertising. Most manual traffic exchanges offer multiple ways to promote your website include page views, banner advertising, downline builders, text advertisements, and emailing their memberships.
Surfing ratios are usually expressed as 2:1 - meaning for every 2 sites you surf you get 1 credit in return, or 1:1 - for every 1 site you surf you get 1 credit in return. Give the manual traffic exchange a try, but remember there is an investment in your time surfing to earn credits. I prefer to be a premium member in a few select manual traffic exchanges, and occasionally surf others.
I've built a section on this website devoted to Manual Traffic Exchanges with some details about each one. I have used each and everyone of them otherwise I wouldn't be endorsing them.