Verizon today introduced its first unlimited data plan since 2011. Verizon Unlimited, which includes unlimited talk, text, and 4G LTE data, will cost $80 per month for a single smartphone or tablet, or $45 per month for four lines. The plan will be available to new and existing customers starting Monday.

Verizon on Monday confirmed that $80 per month for a single line includes its $20 line access charge. It also confirmed that two lines cost $70 each per month, and three lines cost $54 each per month. Electronic billing with AutoPay is required. Taxes and any device payments if applicable are extra.

Verizon Unlimited includes 10GB of 4G LTE tethering per month, with tethering reduced to 3G speeds after the 10GB of usage. The plan includes full HD video streaming, unlike T-Mobile and Sprint's optimized plans that stream video at 480p, and AT&T's opt-out Stream Saver mode that likewise reduces video quality.

The plan also includes calling and texting to Mexico and Canada, and up to 500MB per day of 4G LTE roaming in those countries.

In line with rivals AT&T, T-Mobile, and Sprint, Verizon may de-prioritize customers who exceed 22GB of data usage in a billing cycle in the event of network congestion, so its definition of "unlimited" will be debated. However, Verizon said customers should not expect this de-prioritization to happen often.

Verizon said customers can add a smartwatch or other connected device for an extra $5 per month. TravelPass, offering customers 500MB per day of 4G LTE data while traveling outside of the United States, Canada, or Mexico, reduced to 2G speeds thereafter, is available for an extra $10 per day.

Verizon becomes the last of the "Big Four" U.S. carriers to (again) offer unlimited data. AT&T's unlimited data plan starts at $150 per month when you factor in the minimum cost of a required AT&T U-verse or DirecTV subscription, while T-Mobile ONE starts at $70 per month and Sprint Unlimited starts at $50 per month.