# Does a bitcoin address have to start with a number? No, there are 1, 3 and bc1, which represent the following: The address at the beginning of 1 is P2PKH(pay-to-public-key-hash) address, which is the original address, and is called ordinary BTC address; The address at the beginning of 3 is P2SH(pay-to-script-hash) address, and the internal address also needs to be segwit, that is, the segwit address. The address at the beginning of bc1 is a BECH32 encoded address, an address format developed specifically for segwit, and an segwit address. The address at the beginning of 3 and bc1 are smaller and less expensive than that of 1, which can improve the packaging speed of BTC block. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://help.tokenpocket.pro/en/wallet-faq-en/btc-wallet/does-a-bitcoin-address-have-to-start-with-a-number.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.