A ticker symbol is an English term and has been used on traditional stock exchanges for a very long time. It is a unique symbol used to indicate listed shares and is often an abbreviation of the company for recognition purposes. A ticker consists of letters, numbers or a combination of these and often has one to five characters. These abbreviations used to be created and made as short as possible when manual typing was still required to allow for quick and error-free identification by stock traders. Now it is easy because it simply takes up less space than, say, the full name of a company.
In cryptocurrency markets, each cryptocurrency has its own ‘ticker’ that is used to easily identify the cryptocurrency when trading on an exchange or viewing a trading chart. Some examples of cryptocurrency Ticker symbols are BTC for Bitcoin, ETH for Ethereum, and LTC for Litecoin and so on.
Once a cryptocurrency’s ticker is chosen it does not suddenly change and is the same across every exchange which is also why it cannot be altered.
Unique from other cryptocurrencies, Bitcoin has two tickers. The most commonly used bitcoin ticker is BTC but in some countries this is not allowed, according to regulations here the first letter must be the letter of the country. But what do you do when there is no country or government involved like with Bitcoin, they found something for that, they use the ticker XBT here. So Bitcoin can be found on both the ticker BTC and XBT.
See here an overview of a number of cryptocurrencies with their ticker: