# Pool Lifecycle Any user can create a new pool by calling `newBPool()` on the `BFactory` contract. The caller is set as the `controller` or pool owner. Pools can exist in one of two states: `controlled` or `finalized`. Pools start in a controlled state and the controller may choose to make the pool finalized by calling `finalize()`. Finalize is a one-way transition. While in a controlled state, outside actors cannot add liquidity. A controlled state allows the controller to set the pool's tokens and weights. ### BPTs All pools in Balancer are also ERC20 tokens known as BPTs (Balancer Pool Tokens), which represent proportional ownership in the pool's liquidity. When users add liquidity through `joinPool` or `joinswap*` they receive BPTs proportional to the amount of assets they are adding to the pool. ## Notes BPTs are an opinionated ERC20 token implementation, and have a few subtle differences. `transferFrom` from itself does not require a previous allowance. --- # 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://balancer.gitbook.io/balancer-v2/v1/core-concepts/protocol/pool-lifecycle.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.