what is shared hosting and dedicated hosting.?

[yamunesh kumar]

i am goin to open a website of news,blogs,communities,E-mail,web messenger,matrimonial,online buying and selling,file storing etc. so i need minimum 5gb of webspace and minimum 500 gb of database.
i am expecting around 2,00,000 members will login into my website. i dont know where to take web hosting. and also i want the meaning of what is shared and dedicated hosting. thanks in advance.

[Valdis K]

Note that if you are expecting 2 million members, you *really* should be hiring professionals to do this, rather than asking on Yahoo Answers. You will likely encounter a lot of scaling issues - things that work with 2 or 20 or 2,000 users will fail to work for 2 million.