A startup company or startup is a company

Company

A company is a form of business organization. It is an association or collection of individual real persons and/or other companies, who each provide some form of capital. This group has a common purpose or focus and an aim of gaining profits. This collection, group or association of persons can be...

 with a limited operating history. These companies, generally newly created, are in a phase of development

Business development

A subset of the field of commerce, business development comprises a number of techniques and responsibilities which aim at:1. Researching new types of business/products/services with an emphasis on identifying gaps in the mitigation of needs of potential clients .2. Attracting new customers3...

 and research for market

Market

A market is one of many varieties of systems, institutions, procedures, social relations and infrastructures whereby parties engage in exchange. While parties may exchange goods and services by barter, most markets rely on sellers offering their goods or services in exchange for money from buyers...

s. The term became popular internationally during the dot-com bubble

Dot-com bubble

The dot-com bubble was a speculative bubble covering roughly 1995–2000 during which stock markets in industrialized nations saw their equity value rise rapidly from growth in the more...

 when a great number of dot-com companies

Dot-com company

A dot-com company, or simply a dot-com , is a company that does most of its business on the Internet, usually through a website that uses the popular top-level domain, ".com" .While the term can refer to present-day companies, it is also used specifically to refer to companies with...

 were founded.
Startup companies can come in all forms, but the phrase "startup company" is often associated with high growth, technology oriented companies.