Revenue: Revenue for the year ended December 31, 2023, was approximately $5.4 million, and decreased $1.8 million, or 25%, from approximately $7.3 million for the year ended December 31, 2022. The decrease in revenues was due to decreased unit volumes, particularly in the higher-priced end of the product range (e.g., UAVs and fixed-mount systems). We made an effective exit from the biorisk market and the direct sale of products into the veterinary market. Our traditional core business, selling infrared and other sensor solutions into the industrial market, was relatively steady. We also launched our SmartIR cloud-software product suite in the second quarter of 2023, however we did not earn significant revenue during the year ended December 31, 2023, for our SmartIR cloud-software product. Sales returns were not material for the years ended December 31, 2023, or 2022.
Cost of Goods Sold: Cost of goods sold for the year ended December 31, 2023, was approximately $4.0 million and decreased $1.0 million, or 20%, from approximately $5.0 million for the year ended December 31, 2022. The decrease in cost of goods sold was attributable to the corresponding decrease in product sales, resulting in a decrease in materials and supplies purchased as well as outbound shipping costs, and included the recognition of an inventory write down to net realizable value of $1.7 million in the year ended December 31, 2023.
Gross margin is the percentage obtained by dividing (a) revenue less cost of goods sold (exclusive of depreciation) by (b) revenue. Gross margin for the year ended December 31, 2023, was approximately 27%, compared to 32% for the year ended December 31, 2022. The decrease in gross margin in 2023 compared to 2022 was primarily attributable to the recognition of an inventory write-down to net realizable value of $1.7 million in the year ended December 31, 2023, that was recorded to costs of goods sold. The recognition of this write- down adversely impacted gross margin by 31 percentage points for 2023.
Selling, General and Administrative Expense: Selling, general and administrative expense for the year ended December 31, 2023, was approximately $22.1 million and increased $8.5 million, or 62%, from approximately $13.6 million for the year ended December 31, 2022. The increase in selling, general and administrative expenses was attributable to an increase in share-based compensation of $13.4 million, which was partially offset by a decrease in payroll expense of $2.5 million, a decrease in professional fees by approximately $1.5 million, and a decrease in sales commissions by approximately $0.4 million.
Depreciation Expense: Depreciation expense for the year ended December 31, 2023, was approximately $0.9 million and increased by $0.3 million, or 55%, from approximately $0.6 million for the year ended December 31, 2022. The increase in depreciation expense relates to an increase in additions to property, plant, and equipment during the year ended December 31, 2023.
Interest Expense and Interest Expense, related parties: Interest expense for the year ended December 31, 2023, was approximately $94 thousand and decreased by $21 thousand, or 18% from approximately $115 thousand for the year ended December 31, 2022. The decrease in interest expense was due to the termination of the line of credit agreement in July 2022.
Other (Income) Expenses, net: Other expenses, net for the year ended December 31, 2023, was approximately $44 thousand and decreased $4 thousand, or 8%, as compared to $48 thousand of other expenses, net for the year ended December 31, 2022. The decrease in other income expenses, net was primarily attributable to a decrease in donations and non-operating income and expenses. The decrease in other income was primarily attributable to a decrease in non-operating income and expenses.
Non-GAAP Financial Measures
EBITDA, Adjusted EBITDA, EBITDA Margin, and Adjusted EBITDA Margin
Earnings before interest, taxes, depreciation and amortization (“EBITDA”), Adjusted EBITDA, EBITDA Margin, and Adjusted EBITDA Margin are supplemental non-GAAP financial measures used by management. We define EBITDA as net (loss) income before (i) interest expense (net interest income), (ii) depreciation and (iii) taxes. We define Adjusted EBITDA as EBITDA before share-based compensation expenses and other non-operating income and expenses. We define EBITDA Margin as EBITDA divided by revenue and Adjusted EBITDA Margin as Adjusted EBITDA divided by revenue.
We believe EBITDA, Adjusted EBITDA, EBITDA Margin, and Adjusted EBITDA Margin are useful performance measures because they facilitate comparison of our results of operations from period to period