Browsing is a type of herbivory in which a herbivore feeds on leaves, soft shoots, or fruits of high-growing woody plants such as shrubs. This is contrasted with grazing associated with animals feeding on grass or other low vegetation. Alternatively, grazers are animals eating grass, browsers are animals eating non-grasses, which include both woody and herbaceous dicots. In either case, an example of this dichotomy are goats and sheep; the plant material eaten is known as browse and is taken straight from the plant, though owners of livestock such as goats and deer may cut twigs or branches for feeding to their stock. In temperate regions, owners take browse before leaf fall dry and store it as a winter feed supplement. In time of drought, herdsmen may cut branches from beyond the reach of their stock, as forage at ground level. In the tropical regions, where population pressure leads owners to resort to this more there is a danger of permanent depletion of the supply. Animals in captivity may be fed browse as a replacement for their wild food sources.
If the population of browsers grows too high, all of the browse that they can reach may be devoured. The resulting level below which few or no leaves are found is known as the browse line. If over-browsing continues for too long, the ability of the ecosystem's trees to reproduce may be impaired, as young plants cannot survive long enough to grow too tall for browsers to reach. Overbrowsing occurs when overpopulated or densely concentrated herbivores exert extreme pressure on plants, reducing the carrying capacity and altering the ecological functions of their habitat. Examples of overbrowsing herbivores around the world include Koala in Southern Australia, introduced mammals in New Zealand, cervids in forests of North America and Europe. Deer exclosures are used to determine the ecological impacts of cervids, allowing scientists to compare flora and soil in areas inside and outside of exclosures. Changes in plant communities in response to herbivory reflect the differential palatability of plants to the overabundant herbivore as well as the variable ability of plants to tolerate high levels of browsing.
Compositional and structural changes in forest vegetation can have cascading effects on the entire ecosystem including impacts on soil quality and stability, micro- and macro-invertebrates, small mammals and even large predators. There are several causes of subsequent overbrowsing. Herbivores are introduced to landscapes in which native plants have not evolved to withstand browsing, predators have not adapted to hunt the invading species. In other cases, populations of herbivores exceed historic levels due to reduced hunting or predation pressure. For example, carnivores declined in North America throughout the last century and hunting regulations became stricter, contributing to increased cervid populations across North America. Landscape changes due to human development, such as in agriculture and forestry, can create fragmented forest patches between which deer travel, browsing in early successional habitat at the periphery. Agricultural fields and young silvicultural stands provide deer with high quality food leading to overabundance and increased browsing pressure on forest understory plants.
Overbrowsing impacts plants at individual and community levels. The negative effects of browsing are greater among intolerant species, such as members of the genus Trillium, which have all photosynthetic tissues and reproductive organs at the apex of a singular stem; this means that a deer may eat all the reproductive and photosynthetic tissues at once, reducing the plant’s height, photosynthetic capabilities, reproductive output. This is one example of how overbrowsing can lead to the loss of reproductive individuals in a population, a lack of recruitment of young plants. Plants differ in their palatability to herbivores. At high densities of herbivores, plants that are selected as browse may be missing small and large individuals from the population. At the community level, intense browsing by deer in forests leads to reductions in the abundance of palatable understory herbaceous shrubs, increases in graminoid and bryophyte abundance which are released from competition for light. Overbrowsing can change near-ground forest structure, plant species composition, vegetation density, leaf litter, with consequences for other forest-dwelling animals.
Many species of ground-dwelling invertebrates rely on near-ground vegetation cover and leaf litter layers for habitat. Further, preferential selection of certain plant species by herbivores can impact invertebrates associated with those plants. Migratory forest-dwelling songbirds depend on dense understory vegetation for nesting and foraging habitat and reductions in understory plant biomass caused by deer can lead to declines in forest songbird populations. Loss of understory plant diversity associated with ungulate overbrowsing can impact small mammals that rely on this vegetation for cover and food. Overbrowsing can lead plant communities towards equilibrium states which are only reversible if herbivore numbers are reduced for a sufficient period, actions are taken to restore the original plant communities. Management to reduce deer populations takes a three-pronged approach: large areas of contiguous old for
A file manager or file browser is a computer program that provides a user interface to manage files and folders. The most common operations performed on files or groups of files include creating, renaming, moving or copying and searching for files, as well as modifying file attributes and file permissions. Folders and files may be displayed in a hierarchical tree based on their directory structure; some file managers contain features inspired by web browsers, including forward and back navigational buttons. Some file managers provide network connectivity via protocols, such as FTP, HTTP, NFS, SMB or WebDAV; this is achieved by allowing the user to browse for a file server or by providing its own full client implementations for file server protocols. A term that predates the usage of file manager is directory editor. An early directory editor, DIRED, was developed circa 1974 at the Stanford Artificial Intelligence Laboratory by Stan Kugell. A directory editor was written for EXEC 8 at the University of Maryland, was available to other users at that time.
The term was used by other developers, including Jay Lepreau, who wrote the dired program in 1980, which ran on BSD. This was in turn inspired by an older program with the same name running on TOPS-20. Dired inspired other programs, including dired, the editor script, ded. File-list file managers are older than orthodox file managers. One such file manager is flist, introduced sometime before 1980 on the Conversational Monitor System; this is a variant of fulist, which originated before late 1978, according to comments by its author, Theo Alkema. The flist program provided a list of files in the user's minidisk, allowed sorting by any file attribute; the file attributes could be passed to scripts or function-key definitions, making it simple to use flist as part of CMS EXEC, EXEC 2 or XEDIT scripts. This program ran only on IBM VM/SP CMS, but was the inspiration for other programs, including filelist, programs running on other operating systems, including a program called flist, which ran on OpenVMS, fulist, which runs on Unix.
Orthodox file managers or command-based file managers are text-menu based file managers, that have three windows. Orthodox file managers are one of the longest running families of file managers, preceding graphical user interface-based types. Developers create applications that duplicate and extend the manager, introduced by PathMinder and John Socha's famous Norton Commander for DOS; the concept dates to the mid-1980s—PathMinder was released in 1984, Norton Commander version 1.0 was released in 1986. Despite the age of this concept, file managers based on Norton Commander are developed, dozens of implementations exist for DOS, Microsoft Windows. Nikolai Bezroukov publishes his own set of criteria for an OFM standard. An orthodox file manager has three windows. Two of the windows are positioned symmetrically at the top of the screen; the third is the command line, a minimized command window that can be expanded to full screen. Only one of the panels is active at a given time; the active panel contains the "file cursor".
Panels can be hidden. Files in the active panel serve. For example, files can be copied or moved from the active panel to the location represented in the passive panel; this scheme is most effective for systems in which the keyboard is the sole input device. The active panel shows information about the current working directory and the files that it contains; the passive panel shows the content of another directory. Users may customize the display of columns; the active panel and passive panel can be switched. The following features describe the class of orthodox file managers, they present the user with a two-panel directory view with a command line below. Either panel may be selected to be active; the active panel becomes the working area for delete and rename operations, while the passive panel serves as a target for copy and move operations. Panels may be shrunk. Only the last line of the terminal window is visible, they provide close integration with an underlying OS shell via command line, using the associated terminal window that permits viewing the results of executing shell commands entered on the command line.
They provide the user with extensive keyboard shortcuts. The file manager frees the user from having to use the mouse. Users can create their own file associations and scripts that are invoked for certain file types and organize these scripts into a hierarchical tree. Users can extend the functionality of the manager via a so-called User menu or Start menu and extensions menu. Other common features include: Information on the "active" and "passive" panels may be used for constructing commands on the command line. Examples include path to left panel, path to right panel, etc.. They provide a built-in viewer for the most basic file types, they have a built-in editor. In many cases, the editor can extract certain elements o
A web browser is a software application for accessing information on the World Wide Web. Each individual web page and video is identified by a distinct Uniform Resource Locator, enabling browsers to retrieve these resources from a web server and display them on the user's device. A web browser is not the same thing as a search engine, though the two are confused. For a user, a search engine is just a website, such as google.com, that stores searchable data about other websites. But to connect to a website's server and display its web pages, a user needs to have a web browser installed on their device; the most popular browsers are Chrome, Safari, Internet Explorer, Edge. The first web browser, called WorldWideWeb, was invented in 1990 by Sir Tim Berners-Lee, he recruited Nicola Pellow to write the Line Mode Browser, which displayed web pages on dumb terminals. 1993 was a landmark year with the release of Mosaic, credited as "the world's first popular browser". Its innovative graphical interface made the World Wide Web system easy to use and thus more accessible to the average person.
This, in turn, sparked the Internet boom of the 1990s when the Web grew at a rapid rate. Marc Andreessen, the leader of the Mosaic team, soon started his own company, which released the Mosaic-influenced Netscape Navigator in 1994. Navigator became the most popular browser. Microsoft debuted Internet Explorer in 1995. Microsoft was able to gain a dominant position for two reasons: it bundled Internet Explorer with its popular Microsoft Windows operating system and did so as freeware with no restrictions on usage; the market share of Internet Explorer peaked at over 95% in 2002. In 1998, desperate to remain competitive, Netscape launched what would become the Mozilla Foundation to create a new browser using the open source software model; this work evolved into Firefox, first released by Mozilla in 2004. Firefox reached a 28% market share in 2011. Apple released its Safari browser in 2003, it remains the dominant browser on Apple platforms. The last major entrant to the browser market was Google, its Chrome browser, which debuted in 2008, has been a huge success.
Once a web page has been retrieved, the browser's rendering engine displays it on the user's device. This includes video formats supported by the browser. Web pages contain hyperlinks to other pages and resources; each link contains a URL, when it is clicked, the browser navigates to the new resource. Thus the process of bringing content to the user begins again. To implement all of this, modern browsers are a combination of numerous software components. Web browsers can be configured with a built-in menu. Depending on the browser, the menu may be named Options, or Preferences; the menu has different types of settings. For example, users can change their home default search engine, they can change default web page colors and fonts. Various network connectivity and privacy settings are usually available. During the course of browsing, cookies received from various websites are stored by the browser; some of them contain login credentials or site preferences. However, others are used for tracking user behavior over long periods of time, so browsers provide settings for removing cookies when exiting the browser.
Finer-grained management of cookies requires a browser extension. The most popular browsers have a number of features in common, they allow users to browse in a private mode. They can be customized with extensions, some of them provide a sync service. Most browsers have these user interface features: Allow the user to open multiple pages at the same time, either in different browser windows or in different tabs of the same window. Back and forward buttons to go back to the previous page forward to the next one. A refresh or reload button to reload the current page. A stop button to cancel loading the page. A home button to return to the user's home page. An address bar to display it. A search bar to input terms into a search engine. There are niche browsers with distinct features. One example is text-only browsers that can benefit people with slow Internet connections or those with visual impairments. Mobile browser List of web browsers Comparison of web browsers Media related to Web browsers at Wikimedia Commons