Twitter increases lists limit to 1000 and 5000 accounts on each list

Twitter expands limits on Lists, You can now make up to 1,000 lists, and each list can include up to 5,000 accounts. Previously Twitter allowed users to create up to 20 lists and users can add 500 accounts in each list.

Below I embed the official tweet from Twitter about this limit increases announcement

According to Twitter "A list is a curated group of Twitter users. You can create your own lists or subscribe to lists created by others. Viewing a list timeline will show you a stream of Tweets from only the users on that list."

You can create your own Twitter lists by going lists page