Web traffic

Web traffic is the amount of data sent and received by visitors to a website. This amount necessarily does not include the traffic generated by bots. Since the mid-1990s, web traffic has been the largest portion of Internet traffic. This result is determined by the number of visitors and the number of pages they visit. Sites monitor the incoming and outgoing traffic to see which parts or pages of their site are popular and if there are any apparent trends, such as one specific page being viewed mostly by people in a particular country. There are many ways to monitor this traffic, and the gathered data is used to help structure sites, highlight security problems or indicate a potential lack of bandwidth. 
Not all web traffic is welcomed.
Some companies offer advertising schemes that, in return for increased web traffic (visitors), pay for screen space on the site. There is also "fake traffic", which is bot traffic generated by a third party. This type of traffic can damage a website's reputation, its visibility on Google, and overall domain authority.
Sites also often aim to increase their web traffic through inclusion on search engines and through search engine optimization.
Analysis.
Web analytics is the measurement of the behavior of visitors to a website. In a commercial context, it especially refers to the measurement of which aspects of the website work towards the business objectives of Internet marketing initiatives; for example, which landing pages encourage people to make a purchase. Notable vendors of web analytics software and services include Google Analytics, IBM Digital Analytics (formerly Coremetrics) and Adobe Omniture. Several types of research have been done to evaluate the overall performance of the website. For instance, Shanshan Qi presented the framework to assess the site's technical and service performance. However, the said framework wasn't able to measure user satisfaction with the help of key metrics.
Webmasters can get the data from Google Analytics for these key metrics that will help them to evaluate the website traffic
Measurement.
Web traffic is measured to see the popularity of websites and individual pages or sections within a site. This can be done by viewing the traffic statistics found in the web server log file, an automatically generated list of all the pages served. A "hit" is generated when any file is served. The page itself is considered a file, but images are also files, thus a page with 5 images could generate 6 hits (the 5 images and the page itself). A "page view" is generated when a visitor requests any page within the website – a visitor will always generate at least one page view (the main page) but could generate many more.
Tracking applications external to the website can record traffic by inserting a small piece of HTML code in every page of the website.
Web traffic is also sometimes measured by packet sniffing and thus gaining random samples of traffic data from which to extrapolate information about web traffic as a whole across total Internet usage.
The following types of information are often collated when monitoring web traffic:
Websites produce traffic rankings and statistics based on those people who access the sites while using their toolbars and other means of online measurements. The difficulty with this is that it does not look at the complete traffic picture for a site. Large sites usually hire the services of companies such as the Nielsen NetRatings or Quantcast, but their reports are available only by subscription.
Control.
The amount of traffic seen by a website is a measure of its popularity. By analysing the statistics of visitors it is possible to see shortcomings of the site and look to improve those areas. It is also possible to increase the popularity of a site and the number of people that visit it.
Limiting access.
It is sometimes important to protect some parts of a site by password, allowing only authorized people to visit particular sections or pages.
Some site administrators have chosen to block their page to specific traffic, such as by geographic location. The re-election campaign site for U.S. President George W. Bush (GeorgeWBush.com) was blocked to all internet users outside of the U.S. on 25 October 2004 after a reported attack on the site.
It is also possible to limit access to a web server both based on the number of connections and by the bandwidth expended by each connection. On Apache HTTP servers, this is accomplished by the "limitipconn" module and others.
From search engines.
The majority of website traffic is driven by the search engines. Millions of people use search engines every day to research various topics, buy products, and go about their daily surfing activities. Search engines use keywords to help users find relevant information, and each of the major search engines has developed a unique algorithm to determine where websites are placed within the search results. When a user clicks on one of the listings in the search results, they are directed to the corresponding website and data is transferred from the website's server, thus counting the visitors towards the overall flow of traffic to that website.
Search engine optimization (SEO), is the ongoing practice of optimizing a website to help improve its rankings in the search engines. Several internal and external factors are involved which can help improve a site's listing within the search engines. The higher a site ranks within the search engines for a particular keyword, the more traffic they will receive.
Increasing traffic.
Web traffic can be increased by placement of a site in search engines and purchase of advertising, including bulk e-mail, pop-up ads, and in-page advertisements. 
Web traffic can also be increased by purchasing through web traffic providers who are experts at delivering targeted traffic, however, buying traffic in the past has seen many websites being penalized on search engines.
Web traffic can be increased not only by attracting more visitors to a site, but also by encouraging individual visitors to "linger" on the site, viewing many pages in a visit. ("see Outbrain for an example of this practice")
If a web page is not listed in the first pages of any search, the odds of someone finding it diminishes greatly (especially if there is other competition on the first page). Very few people go past the first page, and the percentage that go to subsequent pages is substantially lower. Consequently, getting proper placement on search engines, a practice known as SEO, is as important as the website itself..
Traffic overload.
Too much web traffic can dramatically slow down or prevent all access to a website. This is caused by more file requests going to the server than it can handle and may be an intentional attack on the site or simply caused by over-popularity. Large-scale websites with numerous servers can often cope with the traffic required, and it is more likely that smaller services are affected by traffic overload. Sudden traffic load may also hang your server or may result in a shutdown of your services.
Denial of service attacks.
Denial-of-service attacks (DoS attacks) have forced websites to close after a malicious attack, flooding the site with more requests than it could cope with. Viruses have also been used to coordinate large-scale distributed denial-of-service attacks.
Sudden popularity.
A sudden burst of publicity may accidentally cause a web traffic overload. A news item in the media, a quickly propagating email, or a link from a popular site may cause such a boost in visitors (sometimes called a flash crowd or the Slashdot effect).
Overall worldwide.
According to Mozilla since January 2017, more than half of the Web traffic is encrypted with HTTPS.
According to estimates cited by the Interactive Advertising Bureau in 2014, around one third of Web traffic is generated by Internet bots and malware.