The Group's principal activities are grocery retailing and the development and monetisation of Intellectual Property ("IP") and technology used for the online retailing, logistics and distribution of grocery and consumer goods. The Group is not reliant on any major customer for 10% or more of its revenue.

In accordance with IFRS 8 "Operating Segments", an operating segment is defined as a business activity whose operating results are reviewed by the chief operating decision-maker ("CODM"), for which discrete information is available. Operating segments are reported in a manner consistent with the internal reporting provided to the CODM, as required by IFRS 8. The CODM, who is responsible for allocating resources and assessing performance of the operating segments, has been identified as the Executive Directors.

During the period, the Group determined it has two reportable segments: Retail and Solutions. The Retail segment provides online grocery and general merchandise offerings to customers within the UK. The Solutions segment provides end-to-end online retail solutions to corporate customers within and outside of the UK. In order to reconcile segment revenuesA to the Group revenue and profit, a third category entitled "Other" shows unallocated costs such as central business activities.

The Board assesses the performance of all segments on the basis of EBITDA. EBITDAA as reported internally by segment, is the key measure utilised in assessing the performance of operating segments within the Group.

The accounting policies of the segments are the same as those for the Group as a whole. Any transactions between the business segments are subject to normal commercial terms and market conditions. Segment results and assets include items directly attributable to a segment as well as those that can be allocated on a reasonable basis.

Segment Revenue and EBITDAARetail
£m
Solutions
£m
Other
£m
Total
£m
2017 (restated)*
Segment revenueA1,346.1108.41,454.5
Segment EBITDAA81.0(6.9)2.676.7
2018
Segment revenueA1,475.8123.01,598.8
Segment EBITDAA82.5(17.9)(5.1)59.5

* 2017 restatement was due to the adoption of IFRS 15 during the year. Refer to note 1.5 for further details.

No measure of total assets and total liabilities are reported for each reportable segment, as such amounts are not regularly provided to the chief operating decision-maker.