Plain definitions of the words that decide which plan fits. Each ties back to the main unlimited eSIM comparison.
Term
eSIM
A SIM profile that is downloaded to a chip already inside the phone, so no plastic card is needed.
Term
Data-only eSIM
A travel eSIM with mobile data but no phone number. Calls and SMS stay on your home SIM.
Term
Daily full-speed allowance
The amount of 4G or 5G data an unlimited plan gives per day before the connection slows down.
Term
Speed after the cap
The reduced speed an unlimited plan keeps after the daily allowance is used. In this comparison it is 512 kbps or 1 Mbps.
Term
Fair use policy
A provider rule that lets networks slow heavy users instead of stating a fixed daily number.
Term
Regional plan
One eSIM valid in many countries, such as a 35-country Europe plan.
Term
Single-country plan
An eSIM valid in one country, usually cheaper per day for a stay in that country.
Term
Fixed plan
A plan with a set amount of data, for example 20 GB for 30 days.
Term
Hotspot or tethering
Sharing your phone's mobile data with a laptop or another phone.
Term
Roam Like At Home
The EU rule that makes roaming charges in the EU match home rates, with fair-use limits. It does not apply in the UK.
Term
Carrier lock
A restriction that ties a phone to one operator and can block a second carrier's eSIM until it is unlocked.
Term
KYC
Identity checks at purchase. Providers state their own policy; check it before you buy.
Term
Activation window
The period after purchase in which you can install and start the plan.
Term
Top-up
Extra data or days added to an eSIM already on your phone.