When you start a new company, you have to give it a name. Next you have to go to the company registrars in your country to register your company name. If that name is already in use by another company, you cannot have that name.
A domain name is exactly like that. Just as a company name is required for an offline business, a domain name is required for an online website. All websites need to have a unique domain name. If that name is already taken, you have to choose another one.
Everyone is a citizen of their respective country. As a registered citizen, you are given an ID Card with a unique number on it. You are also given a name at birth. You are known to your friends and family by name, because it is easier to remember. No one calls or refers to you by your ID number.
Every website is hosted on a server that is connected to the world wide web. Each website is assigned an IP address which is a set of 12 numbers. Just as it is more practical to call you by your name and not your ID number, it is also more practical to type in a domain name rather than typing in the IP address.
Pricing for Domain Names start off around $12 / year for ".com" extensions. Other extensions would cost more. Country specific domain names like ".com.sg" can be even pricier.
More about Domain Names can be found here.
Web hosting can be compared to your office, shop or business address. All your business assets are kept in your office. Your office is one of the many others in a building (usually in a business district).
Web hosting is similar in the sense that all your website files are stored in a web server. Besides your website, other websites are also stored on the same server (office building).
The answer is no.
1) Web hosting company invest a lot in their hardware to ensure fast and reliable hosting. They also invest in softwares to ensure that the data on the system is protected. There are also other softwares to handle emails and complex programs.
2) Web hosting companies also invest a lot in high speed data lines. They also pay a huge amount for bandwidth allocation. The internet access speeds and bandwitdth in your home or office can never match that of a web hosting company. In fact, some Internet Service Provider (the people you buy internet access from), do not allow homes or offices to host websites on their computers due to the additional resources these would consume.
Web hosting costs depend on the type of hosting you choose. The following are the common types:
These will have a large number of websites on one server all sharing the same resources. This can be compared to a building with many houses in it. This is the cheapest option and pricing can start from as low as US5 monthly
You still have other websites on one server but each website would be allocated specific resources. This is like a Semi Detached bungalow.
This is where there is only one website on the server. Can be compared to a Bungalow. Pricing is useally in the hundreds a month.
Learn more about the differences between the three types of web hosting here. http://hosting-server.net/shared-vs-vps-vs-dedicated-hosting-pros-and-cons/
Price range between similar services can also differ between companies. For example, a Shared Hosting package may cost a few dollars in one company but 2 to 3 times more in another.
Some companies attract customers with low prices but set limits on the available resources. If the limit is reached, they shut down the site and force you to upgrade to a higher package. In such situations it is often better to find another host.
Other web hosts might attract you with low offers, but when anything goes wrong, support may be non existant. Never be tempted with low upfront pricing.