Due to technologies, developers can implement within the bounds of your web-browser multifunctional applications, which are available to users from any point connected to the Internet and give functionality comparable to standard applications.

Content of many 2.0-sites is a desert of users and not a web-site. The project itself only realizes opportunities for users. A good example is youtube.com, where all the reels are added by users themselves.

Also web2.0 uses a factor of majority opinion. In practice it is used for rating feature - users are given a possibility to estimate, what is good or bad. Possibly the most active users of those 2 principles described above are social communities.

These are dynamic tendencies to provide an access to all sorts of aggregate data without any restrictions (in form of RSS for instance) and give possibilities to use services freely from outside (in form of API).

So, these are basic characteristics of new generation Internet projects, which are known as Web2.0. It is clear, that all things will be transforming and evolving, but today this kind of projects can be marked out as a separate one, that can be useful to many people all around the world.

Web services - are programs, which are accessible from Web (HTTP protocol), and data exchange is presented in XML or JSON or REST format. As a result software can use web services instead of searching independently required functional (for example to check an e-mail inserted into the form). Unlike standard dynamic libraries such approach has a number of advantages:

• A web service is located on the server of the company-creator, that is why the newest version of data is available there and users don't have to care for updates and processing powers, which are needed for operation performance.
• Instruments for work with HTTP and XML are presented in any modern language of programming, that is why web services are moved to the category of platform-independent.

Asynchronous JavaScript and XML - is an approach to construction of user interfaces in web applications, when a web page uploads necessary data asynchronously without reload. Ajax usage became most popular after Google had started to use it actively while creating its own sites, such as Gmail and Google Maps. Often Ajax is considered a synonym of Web2.0, which is completely incorrect. Web2.0 isn’t attached to some technology or set of technologies, equally well the possibility of asynchronous page update was provided by Flash 4 in 1999.

Simultaneous propagation of information including audio and video content to different pages and web sites, as a rule, with the help of RSS or Atom technologies. The principle consists in propagation of materials titles and links to them. Primarily, this technology was used in news resources and blogs, but gradually it becomes widely adopted.

Web mash-up is a service, which uses other services as info resources, completely or partially, providing a user with new functionality for work. As a result, such a service may become a new source of information for other web mash-up services as well. Thus, forms a whole net of mutually dependent services, integrated with each other.

Key words, which describe the object under consideration or relate it to some category. These are labels, that are attributed to an object to define its place among other objects.

Appearance and fast spread of blogs also fit into Web2.0 conception, creating the so-called rewritable web20.

There is also a possibility to tag the document with key words in the HTTP language.

Usage of development works, which allows to create a community:

• In the notion of site socialization can also be included a possibility of individual site settings and a private zone creation for a user to feel his uniqueness.
• Encouragement, support and faith in "collective intelligence".
• At community formation a great sense has competitiveness and reputation, which allow the community to control itself and set additional goals to be on the site.

When you use third-party services it can bring you certain problems along with advantages:

• Dependency on permanent connection availability (no connection - all the information becomes unavailable or inconvenient to use);
• Dependency on third-party companies' decisions and quality of performance;
• A weak suitability of current infrastructure to carry out complicated calculating tasks in browser;
• Brittleness of confidential data, that are stored on off-site servers.