All the coins existing in the cryptocurrency markets other than Bitcoin are called Alternate Coins or ALT-Coins. Inventors believed that Bitcoin is not enough due to its fundamental weaknesses and cryptocurrencies that are much faster, efficient, and cheaper could be made.
Many altcoins are built based on the basic structure provided by Bitcoin. Therefore, most altcoins are peer-to-peer, require a process of mining by which users solve difficult problems in cracking blocks, and provide secure and inexpensive ways of carrying out web transactions. But Altcoins, even with many overlapping features, vary widely from one another.
eg. Tether (USDT) is a stable coin whose value is pegged to the US Dollar.
Utility Token: These are used in services or apps built on an existing blockchain network. They are built to solve a problem. eg. BAT
Security Token: Also called equity token. They are similar to shares. Company launches these tokens in the form of stakes in their company. eg. Tzero, Polymath
Asset Tokens: These are backed by real-life assets. The asset might be real estate, art, music, or even bonds. The value is derived from the valuation of the real asset. eg. NFTs
Some examples of top altcoins are: