Question: what does frontend and backend mean in programming
[{'answer': 'presentation layer', 'provenance': [{'wikipedia_id': '428625', 'title': 'Front and back ends', 'start_paragraph_id': 1, 'start_character': 106, 'end_paragraph_id': 1, 'end_character': 124, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'data access layer', 'provenance': [{'wikipedia_id': '428625', 'title': 'Front and back ends', 'start_paragraph_id': 1, 'start_character': 148, 'end_paragraph_id': 1, 'end_character': 165, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '428625', 'title': 'Front and back ends', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 436, 'bleu_score': 0.9383908431221111, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14056783004238489101}, 'section': 'Section::::Abstract.'}]}]