“Bioinformatics is the application of statistics and computer science to the field of molecular biology. It includes computational biology, algorithm development, statistics techniques, data modeling and visualization.” – Owen White (2010)
“Bioinformatics is a science where we integrate computer science, genetics and genomics.” – Atul Butte (2010)
上面的定义中提到了统计学和计算机科学在分子生物学领域的应用，以及数据模型和可视化。生物信息学领域早期的前辈们有很多都是从遗传学转过来的。
2011年
【定义8】据说是生物信息学领域最大的专业网站Bioinformatics.org，按照生物信息学发展的不同阶段，对生物信息学的研究内容作了介绍：
生物信息学最宽泛的定义会包含DNA序列或乳房X光片等数据，因此也可以包含医学图像处理的内容。但是平时用到的生物信息学指定的范围要窄的多：主要是指计算分子生物学。
It is debatable whether bioinformatics and the discipline computational biology, literally "biology that involves computation," are the same or distinct. To some, both bioinformatics and computational biology are defined as any use of computers for processing any biologically-derived information, whether DNA sequences or breast X-rays. Therefore, there are other fields, e.g. medical imaging / image analysis, that might be considered part of bioinformatics. This would be the broadest definition of the term. But, in practice, the definition used by most people is even narrower; bioinformatics to them is a synonym for computational molecular biology: any use of computers to characterize the molecular components of living things.
从信息学的角度来看，会强调包含在生物数据中的信息（数据 - 信息 - 知识）：
To others, bioinformatics is a grammatical contraction of "biological informatics" and is therefore related to the computer science disciplines of information science and/or information technology. This definition would thus emphasize the information contained within the biological data, also implying that large amounts of data would be managed and/or analyzed.
前基因组时代的生物信息学基本上就是指序列分析：
Most biologists talk about "doing bioinformatics" when they use computers to store, retrieve, analyze or predict the composition or the structure of biomolecules. As computers become more powerful you could probably add simulate to this list of bioinformatics verbs. "Biomolecules" include your genetic material---nucleic acids---and the products of your genes: proteins. These are the concerns of pre-genomic or "classical" bioinformatics, which deal primarily with sequence analysis.
Fredj Tekaia at the Institut Pasteur offers this definition of bioinformatics:
"The mathematical, statistical and computing methods that aim to solve biological problems using DNA and amino acid sequences and related information."
后基因组时代的生物信息学发生了很大的变化：研究重点从基因本身到基因产物的转移，以及对生物医学实验数据的分析。
The greatest achievement of bioinformatics methods, the Human Genome Project, is practically complete. Because of this the nature and priorities of bioinformatics research and applications have changed. People often talk portentously of our living in the "post-genomic" era. This affects bioinformatics in several ways:
Now that we possess multiple whole genomes, we can look for differences and similarities between all the genes of multiple species. From such studies we can draw particular conclusions about species and general ones about evolution. This kind of science is often referred to as comparative genomics.
There are now technologies designed to measure the relative number of copies of a genetic message (levels of gene expression) at different stages in development or disease or in different tissues. Such technologies, such as DNA microarrays will grow in importance（新的检测技术）.