A travel document is an official paper or booklet that is provided by a national government or an international body under particular agreements. This allows individuals to navigate through border control systems during international travel. Their main role is to assure foreign governments that the person holding the document can return to the country that issued it, and they often come in a booklet shape to collect various stamps and visas. The passport is the most widely recognized type of travel document, offering holders certain advantages, such as the ability to enter some countries without a visa. While passports are the most usual travel documents, there are others designed for people who cannot get a traditional passport, like stateless individuals. They might qualify for special documents like a refugee travel document or a "Nansen passport," which are recognized by certain nations. When crossing borders, authorities expect travelers to show valid travel documents to confirm their identity, their nationality or permanent resident status, and their right to enter the destination. Passports are the most familiar travel documents, containing personal details and space for border officials in various territories to place stamps or visas. Some countries also allow the use of identity cards for border passage, which include the holder's personal information. Importantly, travel document requirements and regulations vary greatly from one nation to another and depend on the specific border control policies in place.

Companion animals, more commonly known as pets, are animals kept not for work or scientific purposes but for the enjoyment and company of their human owners. They range from the traditionally loved dogs and cats to smaller creatures like rodents—including gerbils and hamsters—and extend to birds, reptiles, various aquatic species, amphibians, and even bigger animals like horses. These animals are often selected for their appealing looks, smartness, and engaging personalities, although sometimes people may adopt a pet out of kindness, such as giving a home to a stray. Having pets can lead to multiple advantages for their caretakers. For example, walking a dog can be a way to get exercise and social interaction for both the pet and the owner. More than just physical well-being, pets can provide vital companionship, particularly to those who live alone or older individuals who may not have much social contact. Furthermore, therapy animals, which are specially trained and brought to people in settings like hospitals or nursing homes, can assist in reaching various therapeutic goals. The choice to have pets can stem from the desire for companionship, security for one's home, or simply admiration of the animal's beauty. However, there are hindrances to pet ownership, notably the responsibilities and constraints it involves, such as caring for the pet during travel or having a busy schedule that offers little time to provide proper care. Additionally, the suitability of the living environment can be a concern. Fewer people avoid pets due to dislike — the reasons are more practical in nature, connected to their capability to provide the appropriate level of care and attention the animal needs.

The fundamental aim of pet recovery service is to help pet owners reunite with their lost or stolen companions. These services are varied and cater to different situations where pets may not have an identification tag or do. For pets without tags, options range from online search platforms to employing specialized tactics such as bloodhounds, pet detectives, or community-alert systems that inform neighbors through automated phone calls. For animals with identification tags, there are several ways they can be tracked. Traditional tags may display essential details such as contact information or URLs that direct to databases managed by pet recovery organizations. More advanced tags might use QR codes that link to online records of the pet and their owner. Tattoo registries are another form of database services that support the recovery process. Electronic forms of pet identification have become increasingly popular. Collars can be equipped with electronic trackers which utilize GPS, radio, or Bluetooth technology to locate a lost pet. Some services under these contracts even include active recovery assistance, reducing the necessity for the pet to be found by someone. Additionally, there are devices that send out a call for help to people in the nearby area. Microchip implants, small identification devices inserted under the skin of pets, have been advocated since the 1990s as a durable, collar-free option for pet identification. These chips can be scanned by veterinarians, animal shelters, and certain individuals. In the United States, where the microchip industry is not regulated, various chip types have been developed, yet not all comply with international standards. Although different chips might have required distinct scanners in the past, there is now a movement towards universal readers that can detect and read multiple microchip types.