"What does your website do?" My answer is

Suppose you are an angel investor and I want you to invest my website, you may ask, "Tell me, what does your website do?" I answer, "My website is a platform. You can seek for people to do something for you, and you need to pay them; on the other hand, you can do something for others by spending your time,and you get paid." Does my answer satisfy you? Or how can I improve/better my answer?

Something can be a question,a task, a project, a unit of piecework, an announcement, a survey, etc.

Start with what you have, except shorten it to one sentence, then keep asking "Who cares?" until you get something emotional and specific.

For example:

My website is a platform.

Who cares?

People can ask for work and get work.

Who cares?

It's hard to find good contractors, and it's hard for contractors to find work.

Who cares?

People starting out as contractors might be good, but they don't have connections. Other people want to find those people but also don't have connections. So for them, there's almost no other way to do it.

Who cares?

By connecting people who don't have good existing networks, we're literally able to allow people to create their dream job -- living life without an office, without a boss, and possibly with more job security.

See how I'm getting to a specific story about a person whose life can be changed? That's exciting. That means it's valuable. That means it's easy to sell.

And it means it's easier to get other people to get excited too, which answers your question about raising money.

• You need to give specific examples of what you are talking about.
• Are you targeting specific market/audience/people
• How do you differentiate your site from craigslist? (why would people go there)
• What is your revenue model?
• How many people are using it?
• What is the barrier to entry in this market?

those are just for starters

Your description is too general and vague. Pretend you are explaining the concept to your grandmother and try to do it in one or two sentences.

A nice way to present the functionality of a website is through user stories.

Examples:

I am a web developer with no design skills and need to create a logo for my company. I log on to the website and create a request looking for designers. Designers apply for my request and I choose the one which has the best portfolio. I send a payment to the website with my credit card and wait for the logo to be completed. When it is completed, the payment is transferred to the designer and I can download the logo.

That story is probably too much specific and might not apply to the concept of your website but I couldn't come up with anything better. There is a list of user story examples on Wikipedia.

I like thinking about the simplest way to tell people the benefits a site provides. For your site I would start with "we help connect people that need to do something with someone who can do it". Or something along those lines.
If it is interesting to them, they will ask the appropriate follow questions like what's in it for me etc.

Why don't you show us your platform and let us tell you what we think it does?

"It's a platform" is never a good answer to "what does your app do". The question is not necessarily "what does your app do" but "why should I care about what your app does".

Note that this new question becomes relative to who is asking the question. In this case it is an investor who's goal is to make more money than he put in. If you know this person also likes novel ideas, is very tech savvy, or just likes straight numbers - all of these things should affect your answer.

Mysupersite is a marketplace for
freelancers to buy and sell web-based
services such as graphic design work,
and copy-writing. It's similar to
(well known site) but we offer a
credit system where users can earn
credits to buy services by offering
services of their own. We make money through transaction fees.

Be specific.

"My website is a platform. You can
seek for people to do something for
you, and you need to pay them; on the
other hand, you can do something for
others by spending your time,and you
get paid."

"platform", "people", "something", "them" are all vague and they mean nothing. Essentially you are using a whole lot of nothing to tell me nothing.

It actually is probably just because you are hesitant to divulge the full extent of what you are working on - another mistake.

HTH

I think you may be referring to customer centered design.
A recent blog post talks about this very briefly...
Short, sharp headlines that work