The Leaning Tower of Pisa (Italian: Torre pendente di Pisa) or simply the Tower of Pisa (Torre di Pisa [ˈtorre di ˈpiːza]) is the campanile, or freestanding bell tower, of the cathedral of the Italian city of Pisa, known worldwide for its unintended tilt. The tower is situated behind the Pisa Cathedral and is the third oldest structure in the city's Cathedral Square (Piazza del Duomo), after the cathedral and the Pisa Baptistry. The tower's tilt began during construction in the 12th century, caused by an inadequate foundation on ground too soft on one side to properly support the structure's weight. The tilt increased in the decades before the structure was completed in the 14th century. It gradually increased until the structure was stabilized (and the tilt partially corrected) by efforts in the late 20th and early 21st centuries. The height of the tower is 55.86 metres (183.27 feet) from the ground on the low side and 56.67 metres (185.93 feet) on the high side. The width of the walls at the base is 2.44 m (8 ft 0.06 in). Its weight is estimated at 14,500 metric tons (16,000 short tons). The tower has 296 or 294 steps; the seventh floor has two fewer steps on the north-facing staircase. Prior to restoration work performed between 1990 and 2001, the tower leaned at an angle of 5.5 degrees, but the tower now leans at about 3.99 degrees. This means the top of the tower is displaced horizontally 3.9 metres (12 ft 10 in) from the centre.

The Learjet 25 is an American ten-seat (two crew and eight passengers), twin-engine, high-speed business jet aircraft manufactured by Learjet. It is a stretched version of the Learjet 24.

Learning styles refer to a range of competing and contested theories that aim to account for differences in individuals' learning. These theories propose that all people can be classified according to their 'style' of learning, although the various theories present differing views on how the styles should be defined and categorized. A common concept is that individuals differ in how they learn. The idea of individualized learning styles became popular in the 1970s, and has greatly influenced education despite the criticism that the idea has received from some researchers. Proponents recommend that teachers assess the learning styles of their students and adapt their classroom methods to best fit each student's learning style. Although there is ample evidence that individuals express preferences for how they prefer to receive information, few studies have found any validity in using learning styles in education. Critics say there is no consistent evidence that identifying an individual student's learning style, and teaching for specific learning styles, produces better student outcomes. There is evidence of empirical and pedagogical problems related to forcing learning tasks to "correspond to differences in a one-to-one fashion". Well-designed studies contradict the widespread "meshing hypothesis" that a student will learn best if taught in a method deemed appropriate for the student's learning style. There are substantial criticisms of learning-styles approaches from scientists who have reviewed extensive bodies of research. A 2015 peer reviewed article concluded: "Learning styles theories have not panned out, and it is our responsibility to ensure that students know that."

An LED display is a flat panel display, which uses an array of light-emitting diodes as pixels for a video display. Their brightness allows them to be used outdoors where they are visible in the sun store signs and billboards, and in recent years they have also become commonly used in destination signs on public transport vehicles. LED displays are capable of providing general illumination in addition to visual display, as when used for stage lighting or other decorative (as opposed to informational) purposes.

An LED lamp is a light-emitting diode (LED) product that is assembled into a lamp (or light bulb) for use in lighting fixtures. LED lamps have a lifespan and electrical efficiency which are several times greater than incandescent lamps, and are significantly more efficient than most fluorescent lamps, with some chips able to emit more than 300 lumens per watt (as claimed by Cree and some other LED manufacturers). The LED lamp market is projected to grow by more than twelve-fold over the next decade, from $2 billion in the beginning of 2014 to $25 billion in 2023, a compound annual growth rate (CAGR) of 25%. As of 2016, LEDs use only about 10% of the energy an incandescent lamp requires. Like incandescent lamps and unlike most fluorescent lamps (e.g. tubes and compact fluorescent lamps or CFLs), LEDs come to full brightness without need for a warm-up time; the life of fluorescent lighting is also reduced by frequent switching on and off. The initial cost of LED is usually higher. Degradation of LED dye and packaging materials reduces light output to some extent over time. Some LED lamps are made to be a directly compatible drop-in replacement for incandescent or fluorescent lamps. An LED lamp packaging may show the lumen output, power consumption in watts, color temperature in kelvins or description (e.g. "warm white"), operating temperature range, and sometimes the equivalent wattage of an incandescent lamp of similar luminous output. Most LEDs do not emit light in all directions, and their directional characteristics affect the design of lamps, although omnidirectional lamps which radiate light over a 360° angle are becoming more common. The light output of single LED is less than that of incandescent and compact fluorescent lamps; in most applications multiple LEDs are used to form a lamp, although high-power versions (see below) are becoming available. LED chips require controlled direct current (DC) electrical power and an appropriate circuit as an LED driver is required to convert the alternating current from the power supply to the regulated voltage direct current used by the LEDs. LEDs are adversely affected by high temperature, so LED lamps typically include heat dissipation elements such as heat sinks and cooling fins. LED drivers are the essential components of LED lamps or luminaries. A good LED driver can guarantee a long life for an LED system and provide additional features such as dimming and control. The LED drivers can be put inside lamp or luminaire, which is called a built-in type, or be put outside, which is called an independent type. According to different applications, different types of LED drivers need to be applied, for example an outdoor driver for street light, an indoor point driver for a down light, and an indoor linear driver for a panel light.

LEDVANCE GmbH with headquarters in Garching bei München, Germany is an international company for lighting products and networked light applications that evolved from the divestment of OSRAM Licht AG in July 2016. According to its own information the company employs around 9,000 people in 120 countries. Since April 2018, LEDVANCE is owned by Chinese lighting company MLS CO., LTD. (MLS).

A leg is a weight bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element capable of changing length and rotating about an omnidirectional "hip" joint. As an anatomical animal structure it is used for locomotion. The distal end is often modified to distribute force (such as a foot). Most animals have an even number of legs. As a component of furniture it is used for the economy of materials needed to provide the support for the useful surface, the table top or chair seat.

A leg mechanism (walking mechanism) is an assembly of links and joints (a linkage) intended to simulate the walking motion of humans or animals. Mechanical legs can have one or more actuators, and can perform simple planar or complex motion. Compared to a wheel, a leg mechanism is potentially better fitted to uneven terrain, as it can step over obstacles.

A legendary, mythical, or mythological creature, traditionally called a fabulous beast or fabulous creature, is a fictitious, imaginary and often supernatural animal, often a hybrid, sometimes part human, whose existence has not or cannot be proved and that is described in folklore or fiction but also in historical accounts before history became a science. In the classical era, monstrous creatures such as the Cyclops and the Minotaur appear in heroic tales for the protagonist to destroy. Other creatures, such as the unicorn, were claimed in accounts of natural history by various scholars of antiquity. Some legendary creatures have their origin in traditional mythology and were believed to be real creatures, for example dragons, griffins, and unicorns. Others were based on real encounters, originating in garbled accounts of travelers' tales, such as the Vegetable Lamb of Tartary, which supposedly grew tethered to the earth.

Lego (Danish: [ˈleːɡo]; stylized as LEGO) is a line of plastic construction toys that are manufactured by The Lego Group, a privately held company based in Billund, Denmark. The company's flagship product, Lego, consists of colourful interlocking plastic bricks accompanying an array of gears, figurines called minifigures, and various other parts. Lego pieces can be assembled and connected in many ways, to construct objects; vehicles, buildings, and working robots. Anything constructed can then be taken apart again, and the pieces used to make other objects. The Lego Group began manufacturing the interlocking toy bricks in 1949. Since then a global Lego subculture has developed. Supporting movies, games, competitions, and six Legoland amusement parks have been developed under the brand. As of July 2015, 600 billion Lego parts had been produced. In February 2015, Lego replaced Ferrari as Brand Finance's "world's most powerful brand".