# Channel access tokens
This article explains what channel access tokens are and the different types that we provide.
# What are channel access tokens?
Access tokens are objects that contain security credentials that are used in a token-based authentication process. It allows an app to call an API.
Channel access tokens are access tokens that are used for the Messaging API. LINE supports 3 types of channel access tokens:
- Short-lived channel access token
- Long-lived channel access token
- A channel access token in which the user can specify the expiration
# Short-lived channel access token
A short-lived channel access token is an access token for the Messaging API that is valid for 30 days.
Learn how to Issue a short-lived channel access token in the Messaging API reference.
You do not need to use short-lived channel access tokens that are issued using the /v2/oauth/accessToken endpoint. Instead you can use a long-lived channel access token.
# Long-lived channel access token
A long-lived channel access token is an access token for the Messaging API that has no expiration date.
You can issue a long-lived channel access token from the Messaging API tab by selecting a channel from the Channels in the LINE Developers console.
You can reissue a long-lived channel access token at any time. When you do, the current token becomes invalid. If you need extra time to update the access token in your app, you can delay the time the current access token becomes invalid by up to 24 hours.
# User-specified expiration (Channel access token v2.1)
Channel access tokens v2.1 lets developers specify the expiration date and provides additional security benefits by using a JSON Web Token (JWT) instead of a channel secret. We recommend using this version.
Learn how to Issue a channel access token v2.1 in the Message API documentation.