Simply, Freelancer is an marketing a service individually.
Freelancer is a person who is self employed  and offer service to various clients at a time but not committed with a particular employer for a long time period. In today’s era freelancing  business is a great business opportunity.  there are various types of services provided by freelancer like  technological work such as web programming , web development , HTML , Creative work like graphic designing , interior designing, financial work like bookkeeping, data entry, marketing work include social media marketing , copyrighting, publicity, blog writing , article writing, publicity any various other tasks include virtual assistant,
Freelancer working  is very flexible you can work according to your choice you can set your own working hours, part time or full time on the project of your choice. Along with this freelancer is very easy and quick to start and you can work according to your way and comfort. While you need to deliver what client ask, the way of completing the project is totally depends on you.

There are different freelancer website to find projects on. Some of them are :

Upwork:  It offer different type of project to every freelancer. The projects varies with time some are full time project, some are part time, some are hourly and some are monthly, projects are based on different level also like entry level projects, intermediate level, expert level.  It is best place to start your freelancer work

Freelancer: It is an another platform to earn through your skills you can post your project and receive competitive bids from freelancers of different countries within minutes. One can find perfect freelancer for his/ her job according to their skills and requirement . It is simplest and safest way to get work done online and earn money.

Toptal: Topal is an exclusive network that provide freelancer, designers, finance experts for different countries.

Guru: Guru is a marketplace for freelancer and good for even those who are new to start their freelancer work. You will find decent good paying clients in Guru and the site is easy to handle or manage.

99design: 99 design is a market place for graphic design like web design, logo design and various other design. Its a great platform for graphic designer to show their talent.

PeoplePerHour: PeoplePerHour is a UK based company its function is to give business to the thousands of freelancer who are expert of different field. As they promote the benefits of freelancing as a means to allow people to live more freely, and working where and when suits them according to their choice.